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$1.00 

March 1972 

26009 



magazine 

for radio amateurs 




23 



♦ 



Feature Articles ♦ 23 



CONVERSIONS: T-278 (2m), ART-13 

ARC-3(2m), ESM/1,etc. 

FM ^ "^ ' m P rovements 

Nicad Charger 



General Class Q & A 






CONSIDERABLY 

SPECIAL 
CONSIDERING 

THE 
SPECS 



NEW 2 METER FM TRANSCEIVER Model SRC-146 

Frequency .....143-149 MHz 

■ (2M Hz spread) 

■ Number of channels . . 5 

B Supplied with 146.94 simplex, 

g 146.34/.94 (same plug in 

crystals as SR-C826M) 

R.F. Output „,, 1 watt minimum 

Sensitivity,... ..better than 0,4 

uv/20 DB Q,S, 

Audio output 500 mw 

Meter .♦..♦.monitors battery voltage on 

Tx, S Meter on Rx 

Current drain 400 maTx, 

15 maRxSBY 

Size. 8%" high x 3" wide, x IW deep 

Weight .• ........24 oz., less 

batteries 

Options: external mic, or mie-speaken stubby flexible 
antenna, desk top charger, leather case* 






Suggested 
Amateur 
Net Price 




Consider the new VHF-FM hand held Transceiver by Standard Communications Corp., with ex- 
clusive Astropoint design. For complete specifications and the name of your nearest dealer, write: 

STANDARD COMMUNICATIONS CORP. 

639 North Marine Avenue. Wilmington. California 90744,(213) 775-6284 




magazine 

for radio amateurs 



= 138 MARCH 1972 



FEATURES 

2 Radio Amateur Newspage 

4 Repeater Update 

4 Hot Gear 

5 SSTV Scene 

6 Never Say Die W2NSD 

8 Novice Column 

9 DX Footnotes 
10 Letters 

14 Caveat Emptor 

128 Propagation 

128 Advertiser Index 



STAFF 

Editor-Publisher 

Wayne Green W2NSD/1 

Assistant Editor 

Eric Falkof K1NUN 
Assistant Publisher 

Yvette Grimes WA8ULU 

Philip Price 
Associate Editor 

Jim Kyle K5JKX 
WTW Editor 

Dave Mann K2AGZ 
Advertising Manager 

Lin Green 
Art Director 

Roger Block 
Graphics 

Nancy Estle 

Donna A. Lavoie 
Composition 

Ruthmary Davis 
Subscriptions 

Dorothy Gibson 
Circulation 

Barbara Block 
Comptroller 

Georgiana Sage 
Publications 

Biff Mahoney 
Traffic 

Taylor Sage 
Propagation 

John Nelson 
Drafting 

R. K. Wildman W6MOG 



CONTENTS 

15 Converting The T-278/U Transmitter To 2m W6JTT 

What would a surplus issue be without a surplus article? 

19 Converting The ART-13 W2ISL 

The supposedly dead resurrected. 

23 Improving Your HR2 . WA1 KJI 

Better selectivity, FM article, 

24 Twelve Channels With The Regency HR-2 WA1KJI 

Tsk, another FM article! 

25 MORSE CENTENNIAL Miligram 

Morse died in 1872, His code hasn't yet. 
27 Updating An Old Receiver . „ . . , , W8RHR 

Like for instance a 75A2, 
31 Learning From Emergencies ..................... W2NSD 

Los Angeles SCfVJ report reprinted, 
33 Solid State Tunable IF: Part II . . . . , . K1CLL 

1650 kHz, better than 455, Much better, 
37 Checking Zener Diodes . .WA0ABI 

Using a voltmeter, 
39 General Class Questions & Answers K5JKX 

Practice questions. You read the book, 

48 Technical Aid Group Staff 

An old 73 feature reborn. 

49 Putting The ARC-3 On Two ................ . WA4NAI 

Superbargain 2m rig. 

59 Blown Fuse Indicators .-,... W0EDO 

For ac or dc fuses. 

65 Nonlinear Resistors W6GXN 

Such as light bulbs, thermistors, etc. 

69 Constant Current Charger For Ni Cads . K6MVH 

They're expensive so be nice to them. 

73 The ESM/1 Transceiver WB6BIH 

Solid state pocket CW surplus rig; 

75 Low Cost Transistor RF WA8ZEL 

With typical transmitter circuits, 

101 Updating the W1PLJ Counter . W6GXN 

From Feb. 68 issue of 73. 

109 Circuits, Circuits, Circuits Staff 

Circuits. 

113 Simple Diode Controller W20LV 

"Dimmer" for soldering iron. 

115 Low Pass Filter In Action VE3GSP 

Take that, TV I! 

121 Overseas Patching . K6G KX 

Mars does our public service for us. 

125 Confessions Of A Surplus Hound W20LU 

Neil is an old friend of Wayne's. 



73 Magazine is published monthly by 73 Inc., Peterborough, New 
Hampshire 03458, Subscription rates are $6 for one year in North 
America and US. Zip Code areas overseas, $7 per year elsewhere. 
Two years $11 in US, and $12 overseas. Three years $15, and $16 
overseas. Second class postage paid at Peterborough, N.H. and at 
additional mailing offices. Printed at Menasha, Wisconsin 54952 
U.S.A. Entire contents copyright 1972 by 73 Inc., Peterborough NH 
03458. Phone: 603-924-3873." Subscribers please . , . PLEASE . . , 
note, there is virtually no way for you to renew your subscription to 
73 without receiving at least one extra renewal notice. We've talked 
with our computer and it is adamant about this. The publisher 
stands ready to award himself and his wife a free all expenses paid 
trip around the world, operating from at least 20 rare countries, if 
anyone can come up with a system which will enable the 73 
computer to stop sending renewal notices after a renewal is sent in, 
A copy of this notice autographed by the publisher will be sent to 
all readers who complain about getting a renewal notice after they 
have already renewed. 



MARCH 1972 



1 



Amateur Habto 



MARCH MCMLXXII 



Monthly Hanr 





Reprinted from The Rockland County 
Journal-Sews, Nyack, N»Y* t Dec, 21, 
191 7, 

By Gale Toll in 
Associated Press Writer 
Minneapolis, Minn. 

(API -Hh friends call him *Doc" but 
Felton Jenkins is a physicist-engineer 
and not a physician. He does his 
healing in the basement of his home, 
using eight powerful shortwave radios 
and three telephone lines to deliver 
therapy to wounded servicemen in 
Vietnam, 

it's my way of saying thanks to 
the boys," explains Jenkins. 

For the past four years Jenkins has 
been devoting much of his time and 
money to putting wounded soliders in 
voice contact with their families. Six 
days a week - with Sundays off - he 
is up at 6 a.m. seated among his 
microphones, dials and speakers. He 
handles 25 to 30 contacts each morn- 
ing, in about three hours, and the 
number has run as high as 37 when 
conditions are favorable. 

The soldier's conversations with 
home, Jenkins feels, have medical 
benefits - especially when nervous- 
ness and loneliness figure in the 
wounded man's condition. 



Frequently Jenkins works through 
the Military Affiliate Radio System - 
MARS. Ham radio operator* in Viet- 
nam patch into a telephone which is 
taken to the bed of a soldier in a 
military hospital or on the hospital 
ships Sanctuary and Repose, anchored 
off the Vietnam coast. 

Jenkins is on the U.S, end of the 
transmission. He calls the soldier's 
family by telephone and patches the 
conversation into his radio. 

If the father is at work and the 
mother at home. Jenkins phones each 
of them on different lines and patches 
them into a conference call. The result 
is that the son in Vietnam, father on 
his job and mo tiler in her home can 
chat in a three-way conversation. 

"It's like a party line." said Jenkins. 
"It gives me a certain amount of 
pleasure to be able to do something 
for somebody else. 1 * he said. "I look 
at life as a great big mirror. You look 
in it and smile and it smiles back/* 

His hobby, he said, brings him 
satisfactions that can't be measured in 
dollars. 

As an example, he recalled the case 
of an American solider who had lost 
both legs in Vietnam. 

"His spirits were low, and he wasn't 



Boy Scouts in Radio 

AWARD 

Explorer Post 160 of Fairmont MN 
is sponsoring the Friends of Scouting 
award. The purpose of this award is to 
promote the exchange of ideas, mem- 
ories, planning of future Scouting 
events, develop interest in the Scouts, 
and so on. To obtain the certificate, 
you must work any 25 current mem- 
bers in the Scouts in any country 
where they may be registered. Ex- 
change QSL and GCR list (i.e,, Scout- 
ing position such as Cub, Boy Scout, 
Explorer, Committeeman, Scout- 
master, etcj. Send these with a dollar 
to Explorer Post 1 (>Q, c/o Twin Valley 
Council, Box 22 T Mankato MN 5600 1 . 
SWLs are also eligible for the award. 




Other Scouting awards that are 
available from the Boys* Life Radio 
Club (Certificate Department. B.S.A., 
North Brunswick NJ 08903) are the 
Worked Every Region- B.S.A, This is 
for submission of QSLs verifying con- 
tacts with members of the Scouts in 
the twelve Scouting Regions The 
WAS-BSA is for working Scouters in 
the fifty states. Only SWLs may earn 
the Call Area Specialist certificate for 
verifying stations in all 10 U.S. call 
areas; and the World Listener award is 
issued for submitting cards from 25 
different countries, at least one from 
each of the six continents. 




cooperating with the doctors/" 
Jenkins said. "The doctors were about 
ready to give up on this boy t and they 
asked me if I couldn't arrange for him 
to talk with his parents, 

"The parents happened to live in 
Mexico and it wasn't the easiest thing 
in the world to get them to a tele- 
phone. I had a friend in Mexico pick 
them up and bring them to his radio. 
We patched them through to their 



son. 



i» 



A business executive friend of 
Jenkins heard the conversation in 
Texas on his own ham radio. He broke 
into the conversation and asked to 
talk to the boy. He told him he would 
give him a job. Jenkins and the Texan 
asked another friend, who heads a 
string of business schools to forego 
tuition for the soldier and the third 
man agreed. The amputee w*as flown 
from Vietnam, entered the school, 
was graduated and went to work in a 
business owned by the Texan, 

4 \He turned out to be one of the 
finest employees this firm has ever 
had." Jenkins added. 

Doc Jenkins leaned back in his 
swivel chair, amid his radio equip- 
ment, and summed up his feelings: 
"You some of our work does have 
its dividends/* 



NEW MOBILE XCVR 





Linear Systems announced recently 
that it would be entering the two 
meter FM field with its new SBE 
model SB* 144. The new transceiver is 
ideally suited for the mobile installa- 
tion. It has twelve channel capability, 
ten watts power output, back-lit chan- 
nel selector dial, and combination 
S-RF meter. Comes complete with 
mike t three sets of popular crystals, 
and mobile mounting bracket. Write 
to Linear Systems, J 20 Airport Blvd.. 
Watsomille CA 95076. 



J2eto£ $age£ 



Slews of the World 



73 MAGAZINE 




L to R: Mr. S. £ FeUerman 
K3FEC. of Kensington, Maryland; Dr, 
Robert R. Rodman WB4JAW, of 
Springfield, Virginia; Mrs. Terri 
Simonsr XYL of the late Bert Simons; 
K4YLP; and Mr Wilmer G. Rogers 
WA40PW. ofAshland. Virginia. 

FIRST K4YLP 

MEMORIAL 
AWARD 

PRESENTED 

At a recent meeting of the Virginia 
Amateur Radio Association in Rich- 
mond, Virginia, the first K4YLP Mem* 
orial Award was presented to Wilmer 
G. Rogers WA40PW by Mrs. Terri 
Simons, XYL of the late Bert Simons 
K4YLP, Wilmer, an avid DXer, was 
selected on the basis of the kindness, 
consideration and courtesy shown in 
the field of amateur radio. 

W.G,, as some of his friends eaU 
him, is a past president of V.A.R.A. 
He has given his time unselfishly 
training prospective hams, helping fel- 
low hams with antenna problems, 
organizing club activities such as field 
days and picnics, running phone 
patches and many other things contri- 
buting to the hobby and the Associa- 
tion, 

This award was made possible by 
the Lox & Bagels Radio Club, an 
organization of amateur radio opera- 
tors spanning the east coast. The 
award, an impressive certificate and a 
$25 savings bond, will be awarded 
yearly to the member of the Virginia 
Amateur Radio Association who most 
displays the qualifications exemplary 
of those traits displayed by the late 
Bert Simons. 



IN PUEBLO COLORADO 



REPORT ON HUNTOON TALK 



John Huntoon, ARRL General 
Manager, recently spoke before the 
Pueblo (CO) Ham Club. He comment- 
ed on League activities and policies, 
and made some interesting comments 
about the 200 MHz band. After saying 
that the CBers stand a 50-50 chance 
of getting part of the band, he went 
on to say that the League has not filed 
against the proposal and that the FCC 
has not definitely recommended it 
"If it comes to be, it will hurt, but 
wont hurt much since the advent of 
two meter FM ... If you object, 
please write your League and it [220] 
most likely could be the next repeater 
band." 

Following is a reprint of one man's 
opinion of Hun toon's presentation, 
courtesy of The Grid Leak: 

After Hun toon's lecture he opened 
the floor for questions and discussion 
and our local hams in my opinion 
really put Huntoon through the good 
old fashioned ringer. Some of the 
questions asked were as follows: Why 
QST didn't carry more articles per- 
taining to the subject of FM and FM 
repeaters? Why didn't ARRL print 
manuals concerning the FM mode of 
transmission and repeaters? Why is 
QST so difficult to read and under- 
stand? Why is the FCC calling in at 
this time Technician and General con- 
ditionals for re-examination? What are 
the chances of the CBers getting the 
2 20 band? 

Mr Huntoon stated that in the 
future there will be more articles 
concerning FM and FM repeaters. 
There is an ARRL manual on FM in 
the process of being prepared and 
should be ready either in the latter 
part of 1972 or the early part of 
1973. QST will be more readable in 
the future. Last year he felt the 
chances of the CBers getting the 220 
band were 10 to 1 against their getting 
it. but as of today he felt that they 
stood a better than 50-50 chance of 
getting this band, 

His answer to the questions about 
the Techs and Conditionals kind of 
gave me a sour taste in my mouth and 
left me with the feeling that the 
ARRL as an organization is rather 
inept and really isn't in too much of a 
hurry to see the amateur ranks grow. 



He stated that in his opnion many 
conditional licenses were obtained 
fraudulently and if a ham is really 
interested in ham radio recall by the 
FCC should hold no fear for the 
operator. At this point if it hadn't 
been for Chuck Chambers K0YFR 
holding me , 1 might have fallen either 
to or through the floor. 

Most of the hams at the meeting 
disagreed with the above mentioned 
answer for a number of reasons. I for 
one disagree with his answer and the 
FCC actions for the following reasons: 
The average Tech conditional because 
of the bands allotted to him has very 
little opportunity to use CW. The 
average General conditional usually 
uses phone as is the practice amongst 
most hams. And besides when an 
individual gets into ham radio and 
starts operating he usually forgets all 
the fine points of theory he learned 
when he was studying for his exami- 
nation. 

Most licensed professions that I am 
acquainted with never require their 
licensees to ever have to take another 
exam to prove their proficiency, even 
if the individual has been licensed 
under a "grandfather clause." Now I 
realize that ham radio is not a pro- 
fession, but it is a licensed hobby and 
consequently 1 feel that the law as it 
applies to licensing anything should 
apply. And the law on that point is 
that it is illegal and a clear example of 
double jeopardy when an individual 
has to be subjected either to trial for 
the same offense or to examination in 
a profession or hobby for which he 
already has been issued a license. 

In private conversation with Mr. 
Huntoon, I told him 1 felt that the 
ARRL doesn't seem to go too far out 
of its way battling for hams when 
various legal situations arise. He told 
me that to a great extent I was correct 
because the ARRL lacks funds to get 
involved in legal and other situations 
that may arise all over the country, 

Unions defend their union mem- 
bers. 

Professional associations defend 
their members. 

Why shouldn't ARRL defend its 
ham members? 

Dr. Morris Levinson WB0BSV 



At Long Beach 



YL'S TO MEET 



Women amateur radio operators 
will gather at Long Beach, California 
daring the long holiday weekend of 
May 26-28, 1972. The Sixth Inter* 
national YLRL Convention marks the 
33rd year of this organization's activi- 
ties, As 33 has become the traditional 
signnoff for QSO's between YL's, the 
33rd birthday celebration is a high 
point in the history of this organiza- 
tion of women amateurs from all over 
the world, now numbering close to a 
thousand members. The convention 
will have headquarters, operating sta- 
tion, meetings, entertainment, birth- 
day luncheon and l6 cruise" banquet at 
the Edge water Hyatt House on Pacific 
Coast Highway overlooking the Long 
Beach Marina, 

The YL's will entertain their OM's 
with a tour of the Swan Electronics 
plant in Oeeanside on Saturday, May 
27th, returning to the Edgewater for a 



luau. A visit to the Queen Mary and 
other harbor points of interest is 
planned. But the event these YL's 
anticipate with the greatest interest is 
meeting in "eyelash QSOV the YL's 
they have met on the air or will look 
for on the air once they return to 
their home QTH and with whom they 
share their exciting hobby in friend- 
ship, public service and ever-expand- 
ing horizons, Los Angeles YL's host* 
ing this convention encourage all who 
attend to come supplied with a pocket 
full of snapshots for "swaps 1 * to ex- 
change with calls and autographs. 
They look forward to seeing Darleen 
Souligny WA6FSC, who spent much 
of 1971 traveling and meeting DXers 
around the world. This year's YLRL 
President who will preside at the 
convention is Mae Hipp K7QGO of 
Sparks, Nevada. 



HOT GEAR 



HR2A, S/N 04-6208, stolen from car 
in New Orleans LA, E. A. Shaw, P.O. 
Box 1346, Pascagoula MS 39567. 
W5FXX/5. 

Heath SB1G2, S/N 132-128107, 
Warren Singer, 13721 Lynn St., Apt. 
8, Woodbridge VA 22191 

(703-491-2257). 



List from Past Issues: 

Mf r\. Model, Ser. No. 
HattL, SR46A. #446100 
Reg,, HR-2, #04-03505 
Sonar, FM3601, #1003 
Coll.. 75 A4, #804 
GE, Portable, #1041218 
Coll., 75SE-B, #15640 
Coll., 21 S3, #12000 
Coll.,516F2. #1649 
Simp. Mod-A. #35457 

SBESB-33 #103906, 



Owner Issue 

WAIEMU 9/71 

WA5BNM 11/71 

WB2ARM 11/71 

W0MGI 1 2/7 1 

K2AOQ 1/72 

Col.SLU. 1/72 

CoI.SlU. 1/72 

Col.SLU. 1/72 

W2PWG 1/72 

WASJGU 2/72 



Heath HW22A #907-18375 W 1 BDX 2/72 

National HR050 #280019 WA5DQF 2/72 

Hallicrafters SRI 60 #416000-108039 

K9YVA 2/72 

Drake TR3 #3858 WA9EYL 2/72 

Collins KWM2A#13S1 5 ARRLHQ 2/72 

M, Godwin 
Collins 3 12B4 #59920 
Col 30L1 #40084 
Col MP1 #44507 
Col MM 1 (mob. mike) 
MisGC minispkr. Sgt. Hopkins 2/72 

Wilm. DE Police 
Sw;m SW 1 74 #426^5 W0AXT 2/7 2 

Reg. HR2A #04-05896 K4GBL 2/72 



PLEASE INCLUDE YOUR ZIP CODE 
WHEN YOU WRITE 73. 



■■ 




:•:■: :o:c;:::-.-:^: :■.■:•.-:•:■:. ::>:.•.:■•:-.:• :. .: :.. :: 
..■■■ ->■■■.*■■■ -■■■■■-'.■ .■_..-.■ ■.-.. ...■■■■■..-.. ■■■■■-.■ ■ ■ ■■■■ 



l-^- 



REPEATER UPDATE 




STENING 
76 88 73 70 64 82 




.-.- :^~ ^^f-^/fT^T^^y ^vg l vo ^^So 




CO K0PHF 
FL WB4QEL 
1L W9MJL 
MD K3BEQ> 
OR W7DXX 



Pueblo 28-88 

Orlando 16,34-76 
Danville 22-82 
now WA3KWG 
Mt. Scott 34-94 

-L 4_- . -J mj JL* * +J £* J 

T2.88 29.68 



CANADA 
Ontario 

VE3KCR 

VE3KER 
VE3LAC 



Chatham 34-94 
(projected37-76) 
Kingston 34-706 
London 46-706 



Thanks to W4FZX. WB9FOP, 
VE3CSK, VE3RL. 

Amateur Radio, August 1971. New 
Zealand has: been working on a 2 
meter band plan for the country. In 
the draft plan we received, they have 
made provision for all modes of opera- 
tion. There are FM simplex channels 
every 50 kHz from 145.8 to 146.2 
MHz, with 145.85, 146.0 and 146,15 
MHz, as the prime channels. 146.0 
MHz to be first. On the FM repeater 
side they have allocated four channels 
on 700 kHz spacing, A pity, as it does 
not make them compatible to Austra- 
lia. Inputs on 146.3, 35, .4 and .45 
with the outputs on 145,6, .65, .7 and 
.75. The three-channel AM repeater 
systems have inputs on 144.6, .65 and 



WITH 
THE 
FCC 



tr iq | I' i ■ | J i ■■■■■■ ■ 

llfrthai, 4DU*_-> ti ■ ■■•■ '|I"'H'P 

l ■ ■■. ,m ■ . i r | !■■>■ 



^^ 



„ .... *i-i fc-T* 







:*l hL ■ ■ ■ i .i ii I II 



There have been some questions 
about FM deviation used on six and 
ten meters. The following reply to a 
letter of inquiry by W6YAN clarifies 
the issue: 

Section 97.65(c) of the Commis- 
sion's rules require that F3 emissions 
used between 50.1-52.5 MHz occupy 
the same bandwidth as a A3 signal or 
6 kHz. Part 2 of the Commission's 
rules {§2.202) defines bandwidth of 
an F3 signal as equal to two times the 
maximum modulation frequency plus 
two times the quantity one half the 
difference between the maximum and 
minimum values of the instantaneous 
frequency. (B n = 2M + 2D). As you 
can caluculate, if the audio modula- 
tion is 3 kHz, D must be zero, 

FCC-Amateur Rules Section 



-» 



# 



A. Prose Walker, chief of the Ama- 
teur and CB Division of the FCC, has 
indicated FCC thoughts about these 
services. In an interview with CB 
Magazine {January, 1972) Mr, Walker 
answered several questions that are 
foremost on the minds of many hams. 
As far as a license without a code test, 
there is a possibiJity that such a 
provision will be made. When asked 
about this, he stated, "The Interna- 
tional Radio Regulations of the ITU 
to which the United States is a signa- 
tory, contains various provisions relat- 
ing to the operation of radio stations. 
Article 41 , paragraph 3(1) states that 
Administrations may waive the re- 
quirement for capability in Morse 
code in the case of amateur stations 
making use exclusively of frequencies 
above 144 MHz, For years we have 
been told that one of the reasons why 
more licensees in Citizens Radio do 
not progress to Amateur Radio is 
because of the requirement for the 
code. Even though the code require- 
ment for the Novice and Technician 
license is only 5 words per minute, 
indications are that it is still a hind- 
rance. We believe that 5 words per 



.7 with the outputs on 145.725, .775 
and .825. 144.8 MHz, is set aside as an 
RTTY net frequency. The beacons are 
on^the "hundred** equal to the call 
area, e.g, ZL1 on 145.1, ZL2 on 
145.2, ZL3 on 1453, and ZL4 on 
145.4 MHz. The segment 144.0 to 
144.1 MHz is set aside as DX and 
experimental working. 144.1 to 144.5 
MHz is a general working segment. 
Federal Repeater Secretariat. 



minute is a bare minimum, and is not 
difficult to achieve with proper appli- 
cation of effort. Nevertheless, we are 
actively considering amending por- 
tions of Part 97 of the Rules and 
Regulations for the Amateur Service 
which would permit operation above 
144 MHz without the code require* 
mem included in the examination. In 
all likelihood, there will be two classes 
of no-code license. One will be 
roughly equivalent to the General 
Class but for VHF and UHF opera- 
tion; and the other equivalent to the 
Advanced or Extra Class covering only 
above 144 MHz. The examination will 
be completely new and will cover 
VHF and UHF related technical mat- 
ters. Another aspect we are also con- 
sidering is to possibly require the 
licensee of an Amateur Repeater sta- 
tion to hold the higher class of 
license." 

The EIA proposal that would elimi- 
nate several megahertz of the amateur 
220 MHz band and change them into 
a Class D Citizens Band was another 
topic for discussion. Mr. Walker had 
this to say about RM-1747: "We have 
given it considerable attention over 
the past months since it was filed with 
the Commission. The decision has not 
yet been taken whether to issue a 
Notice of Proposed Rule Making. 
There are various factors involved 
such as the priority of use of the 220 
MHz area of the spectrum; the possi- 
bilities of other needed uses if a 
change in the existing allocation were 
to be considered; what would happen 
to 27 MHz if the band for CB were 
changed; whether the same type of 
operation as now exists on 27 MHz 
would also prevail on 220 MHz and 
what would be the ramifications of 
that; whether the CB user actually 
wants or needs such a drastic change 
in the spectrum allocation for the 
Service or whether the proposed plan 
is primarily for the benefit of the 
manufacturer in opening up a new 
market. Details of all these and other 
considerations would take up a great 
deal of time. Let me assure you again 
that we are giving most serious con- 
sideration to RM-1747, but we are not 
on the verge of a decision as to 
exactly what is the best course to 
follow. You know that we are charged 
with the administration of the CB 
Service and therefore we must give 
full consideration to the maximum 
benefits to be derived by the licensees 
from whatever course is followed. 
Obviously, no one would desire open- 
ing up a new area of the spectrum 
without the assurance that the opera- 
tion to be expected would be an 
improvement over that now obtained 
on 27 MHz. You also know that the 
band 220—225 MHz is currently allo- 
cated to the Amateur Service on a 
second priority basis to Government, 





BULLETIN 



HAM INJURED IN 
ATTACK BY 'QST' 

by WA1NQJ (Special from The 
Squelch Tale) 



K1RGQ was viciously attacked by 
QST Magazine recently. However, 
showing true heroism and amateur 
spirit, he rescued his Swan and 
Regency, sustaining an injury to his 
arm in the fray. John assured us that 
he is now fully recuperated. 

While tuning in on K1FFK-6 
meters - and eagerly peaking his watt- 
meter, John saw that his homemade 
bookshelf containing many, many 
years of back issues of QST Magazine 
was beginning to topple. If things had 
fallen in the direction they were 
headed, all of his gear would have 
been knocked off his operating table 
to oblivion, John, anticipating damage 
to his gear, threw himself over it; the 
magazines and bookshelf fell, throw- 
ing John to the floor and pinning him 
there. Alone in the house, it took 
John approximately an hour to extri- 
cate himself. He is happy to report 
that his arm is fine now and that none 
of his gear was damaged. 



No doubt the Amateurs would like to 
be heard whenever the moment is 
propitious, such as the possible issu- 
ance of a Notice of Proposed Rule 
Making, I repeat, we have not yet 
reached a conclusion as to the manner 
in which we shall dispose of 
RM-1747,' 1 

As for the current abuses of the 
Citizens Band on 27 MHz, Mr, Walker 
mentioned that working skip is not 
the main problem; "Actually, there 
are many others of a more serious 
nature which have nothing whatsoever 
to do with longdistance transmission; 
failure to identify, use of pseudonyms 
in lieu of call signs, foul and obscene 
language, threats of bodily harm to 
others, use of high-power linear ampli- 
fiers, operation on frequencies not 
allocated to the Service, intentional 
interference, and many others which 
reduce the potential usefulness of the 
Service for those who wish to use it 
for the purposes intended /' He men- 
tioned that these violations are being 
taken into consideration. He further 
indicated that a very large amount of 
self-regulation must prevail if the Citi- 
zens Service is to perform its intended 
function, "One of the most useful 
procedures would be to emulate the 
degree of self-regulation that has pre- 
vailed in the Amateur Service for the 
past 50 years." 



SEMICONDUCTOR 
NEWS 

IV1_V¥W D Thorpe 

RCA says goodbye to germanium 
and silicon small-signal transistors. 

RCA's Solid State Division has de- 
cided to phase out over one hundred 
types of small-signal transistors. In- 
cluded in the cutback is the whole line 
of small-signal silicon transistors. The 
devices discontinued are as follows: 
Silicon: 2N2475, 2N3241, 2N3261, 
2N35I2, 2N3932, 2N3933, 2N4068, 
2N4069, 2N4Q74, 2N4259, 2N4390, 
2N5180, 2N5183, 2N5184, 2N5I85, 
2N5186,2N5187,2N5I88, 
Germanium: 2N388, 2N398, 2N4G4, 
2N1302, 2N1303, 2N13Q4, 2NI3G5, 
2N1306, 2N1307, 2N1308, 2N1309. 
40,000 Series: 4023 1 , 40232, 30233, 
40234, 40235, 40236, 40237,40238, 
40239, 40240, 40242, 40243,40244, 
40245, 40246, 40354, 40355,40397, 
40398, 40399, 40400, 40405,40413, 
40458,40519. 

GE Discontinues IC Manufacturing 

GE has quit making their popular 
line of audio ICs such as the PA234, 
PA237, PA246, PA263. Most of these 
are already in short supply — for ex- 
ample there are no more PA237 de- 
vices to be had. Best bet for audio ICs 
include the Motorola MFC9020, 
MC1316P, RCA CA3020, CA3020A 
and Plessey SL403D. 

The RCA devices are already hard 
to find, for example the popular 
2N5188 and many of the 40,000 
series are in short supply. In most 
cases, a suitable replacement device 
can be used so the situation isn't as 
bad as it first may appear, If you need 
help in locating replacement devices 
for RCA transistors or GE integrated 
circuits contact Circuit Specialists Co. 
Box 3041, Scottsdale AZ 85257. 



SSTV 
SCENE 



Among the notes of special interest 
this month is the addition of XW8AX 
to the SSTV ranks. Since Asia has the 
lowest amount of SSTV activity, I'm 
sure he will be quite busy handing out 
those 'Eyeball QSO's and instant 
QSL's/' This, at last, makes worked 
all continents on SSTV a reality for us 
all . . . provided you can catch him. 
Try listening around 1 200- 1 300 
GMT Saturdays and Sundays on 
14,230 kHz. You SSB DXers take 
note here . . . you can work anybody 
in Asia for an Asian QSO. We have to 
work a specific station and swap not 
only signal reports, but pictures as 
well DXing Supreme, eh? 

(continued on page 13) 



& 



■■1 



■i 




GOING THROUGH CHANNELS 

One of the biggest features oi FM 
communications is the concept of 
channelizing. What a difference this 
makes! One wonders what might 
happen to low band communications 
if we could introduce this novel 
concept there. 

With two kHz channels in the 20 
meter phone band we could have 75 
sideband channels in that 150 kHz 
wide band. Would we have better 
communications this way or worse? 
We might have essentially 75 going 
round tables during the more active 
hours, but the less time that each 
operator could talk would make it a 
lot easier for everyone- Or would it 
develop that we would have 75 
channels all sounding like the CB 
channels? Would we have 
multi-kilowatts and giant beams 
blasting through on each of the 
channels, ignoring the lower powered 
peasants? It has worked well on two 
meters, perhaps it might on 20. We 
could try. 

If we were to start with one 
channel on twenty meters and then 
gradually expand this to two, 
three , . . etc., perhaps we could see 
how we might go with channels. An 
FM-sideband interface which would 
permit a two meter repeater to work 
cross-band to twenty on a national 
channel could be a starter. Perhaps 
something like 14,250 kHz? This isn't 
a bad spot It is a bit befow the SSTV 
group and above most of the serious 
DXing, It is below the General Class 
band and the intensive QRM of the 
nets and frustrated rag chewers who 
operate there. Channel two could be 
14,248 . . . etc. 

Think of the benefits to everyone. 
It would, first of all, make a lot more 
fun for the two meter FMer, 
expanding his horizon to the world. It 
would bring FM to the attention of 
the low banders, whetting their 
interest and perhaps speeding up the 
swing to FM of more old timers. It 
would encourage more repeaters to 
handle the traffic and rag chewing 
which would develop. And if 
channelization helps on twenty 
meters, that would be the best benefit 
of all! 

The legal problems of Techs using 
20 meters by proxy have been covered 
in depth elsewhere. 



EDfTOR/AL BY WAYNE GREEN 

CONTROL 

The key to the question of legality 
of Techs being repeated out of the 
Tech bands lies in the matter of 
control. If the FCC decides that the 
carrier coming from a Tech station is 
controlling the transmitter of the re- 
peater, then the Tech would be in 
control of the output carrier and 
would be required to be sure it was 
within a band his license called for. 

But is the Tech carrier really in 
control? Lets look at that situation 
more carefully. Let's think a little 
more deeply about the word "eon- 
trol/' Our problem here is one of a 
lack of definition . . , one where Techs 
might have one definition and the 
Commission another. 

Perhaps we can clear things a bit by 
drawing a parallel. Let's take the case 
of an Advanced Class station on 20 
meters. Sideband, of course. As nor- 
mally operated this station used VOX 
(voice on transmit), a gadget which 
turns the transmitter on when some- 
one speaks into the mike. When a 
visitor speaks over this station his 
voice turns on the transmitter, even 
though he has no amateur license at 
alL This is quite legal as long as the 
licensed amateur is present and is *'in 
control" of the station , . . which 
means in essence that he can turn off 
the station if something goes wrong. 
Control then is the ability to turn a 
transmitter on or off in an emergency 
and not the routine turning on and off 
of the transmitter. 

This is exactly the situation we 
have with repeaters. While the carrier 
from a Tech does indeed actuate the 
repeater transmitter, this does not 
interfere with overall control by the 
licensee of the repeater. Control of a 
repeater may be via 450 MHz link, by 
phone line, or other accepted means, 
but this is the control and the FCC 
will have to make sweeping changes in 
their interpretations of the rules be- 
fore they can prevent repeaters from 
relaying Techs into the General parts 
of the two meter band . . . or even 
into the Extra parts of 75 meters! 

WHAT ISAM? 

Those readers who are theory 
minded may be able to commiserate 
with me on the problem of amplitude 
modulation. I've read a lot about it 
down through the years and felt there 



must be something basically dense 
about me since none of the explana- 
tions made sense. Why, if we are 
varying the amplitude of a transmitted 
carrier, does the carrier not vary in 
amplitude? And those sidebands, what 
are they and where did they come 
from? 

Pity a chap named Robinson out in 
Michigan who has managed to come 
up with a real amplitude modulated 
carrier and has found that he has 
patent problems because everyone, 

including the Patent Office thought 
that "amplitude modulation*' resulted 
in the carrier varying in amplitude. 

The process that we have always 
considered as amplitude modulation 
was actually a high level mixing of 
audio and radio frequencies, resulting, 
as always, in mixers, in the sum and 
difference of the two mixed fre- 
quencies plus the two original fre- 
quencies, 

I don*t suppose you really want to 
be bothered with an attack of theory 
like that, but the concept hit me and I 
thought 1 would pass it along. 



NORTHEASTERN REPEATER 
MEETING 

Representatives of several of the 
repeaters in the New York and New 
Jersey areas got together in early 
January to hash out problems of 
repeater interference and ? to the pleas- 
ure of all, came to agreements. This is 
certainly a very welcome step ahead. 

The basic agreement was for re- 
peaters to shift to 600 kHz spacing 
and thus bring about the orderly 
growth of repeater use on two meters. 
A full report on the meeting will 
eventually filter through, but the 
word is that WA2SUR in New York 
will shift from 19-73 to 1 3-73; that 
WA2UWR in Paramus will change 
from 28-79 to 19-79, WA2YYQ on 
Staten Island will go from 25-88 to 
28-88, WA1KGK in Trumbull will 
change from 22-76 to 16-76, 
WA1KGD in New Haven from 1 1-61 
to 01-61, and so on. It is possible 
that Kl MNS in Deny NH will go from 
25-76 to 25-85, but this leaves a 
question about WA1KFX which was 
31 88 and was apparently being set 
up on 25—85 as soon as power was 
restored on Mt. Snow ... it would 
clobber MNS, WA1JTB in Greenwich 

■ 

is still in doubt too, but may go 
31-91, 

This rash of agreements will 
undoubtedly bring about even more 
with KIFFK expected to shift to 
04-64, WA1KGS (Waltham) to 
01-61, WA1KHA to 25-85 in 
Torrington, WAIKGQ to 19-79, etc. 

The move toward a national 
transceive channel got a boost too, 



with an agreement to go 146,52 
transceive throughout the New 
York -New Jersey areas. The next 
step is to encourage manufacturers 
and distributors to see that all newly 
sold transceivers come out with this 
pair in them instead of the old 146.94 
pair which has muddied the waters so 
badly in several major areas such as 
New York City and Chicago. 



The FM scene changeth fast and it 
is difficult to try and keep up with 
events in a monthly magazine. 

Saroc came and went in early Janu- 
ary, There were more exhibitors and 
visitors than ever and, despite a lack 
of planning as far as the speaking 
program went; everyone had a good 
time. FM was the watchword, with 
hand units everywhere and the regular 
channels filled around the clock, often 
sounding more like CB than amateur 
after the frequent cocktail parties. 

The Pallisades Amateur Radio Club 
group turned up in force and brought 
with them their own instant repeater 
(right out of the October 73, by the 
way) so everyone could use their 
weird Los Angeles crystals while visit- 
ing Las Vegas (146.61 in, 14733 
out!). This enabled all of the club 
members to use their mobile and hand 
units during their stay without chang- 
ing them over to the 34-94 Nevada 
repeater channels* 

With the idea of promoting some 
organization of the FM growth in the 
northeast, we started the Repeater 
Bulletin back in January, This publica- 
tion is being sent free to everyone 
using the New England repeaters and 
the reaction to the first 24-page i&sue 
was universally enthusiastic. The 
second issue, a 32-page bulletin, is 
now out and the publication seems to 
be achieving its objective of providing 
a forum for discussion of development 
of FM in the New England area. 

In line with the idea of helping New 
England repeater groups to coordi- 
nate, an FM Symposium was planned 
for February 1 2th. Apparently this 
threw some of the vested interests 
into panic and a swift behind the 
scenes effort was made to set up an 
FM organization which would pull the 
rug out from under the symposium. 
Rather than being dismayed at this, I 
think it is a good move. The objective 
is to set up a system of self-govern- 
ment and the agreements made so far 
are quite in line with this. There is still 
more to be done, obviously, and 73 
will do whatever it can to help this 
along. 

To those who are afraid that 73 or 
Wayne Green are going to try and take 
"'power' T away from them, I say that 1 
seek only the power of reason. I do 
not want to run any tiling or dictate, 




NEW WINCHES 
MODERNIZE TOWERS 

Tri-Ex Tower Corporation of 
Visalia, California, has announced the 
release of two new electric winches 
for crank-up towers. The 1 2 volt 
electric reversible winch is sold with 
power cables; the battery in weather 
tight case and 1 10V AC battery charg- 
er are optional. It has forward and 
reverse speeds for raising and lowering 



but I do want to be heard and I want 
to help anyone else with ideas to be 
heard ... I ask no more than that. 
Power all too often means running 
roughshod over people with ideas that 
differ from yours and it is this power 
that 1 dislike. 

The symposium should be interest- 
ing. It will be reported in the next 
issue of 73. The first session of the 
symposium will tackle frequency 
synthesis and will feature a panel 
discussion with Ed Clegg and Andre 
(Vanguard Labs). Gil Boelke may also 
be present, if the new Bara synthesizer 
is completed in time. 

The second session will tackle need- 
ed FCC regulation and this will be 
reported in lull to the FCC. I think we 
amateurs want to be self-policing and 
to have a strong say over our own 
rules. Sessions such as this should help 
us in this. 

The third session will attempt to 
get the representatives of the New 
England repeater groups to set up a 
frequency board which will help new 
repeaters to find channels and assist 
present repeater groups in working 
toward a minimum of interference. 

Following the third session will be 
the banquet with Jean Shepherd 
K20RS as the speaker. Jean, one of 

hamdoms best known writers and 
humorists, is heard nightly over WOR, 
WGBH and other stations, has a book 
on the current best seller list, and has 
a television series (Jean Shepherd's 
America) which has been highly ac- 
claimed. Few of us have missed the 
hilarious stories he has had published 
in Playboy, which have won him their 
coveted humor award for several yeaTS 
running. 

After the banquet there will be one 
last technical session tackling the pros 
and cons of changing the current 600 
kHz spacing to 1 MHz channel spac- 
ing. The arguments are formidable for 
I MHz, so it is entirely possible that 
the repeater representatives might opt 
for that on the spot. We shall see next 
month. 

. . , W2NSD 




the tower, and a level wind assembly 
to keep the cable from stacking. Brak- 
ing is immediate, without coasting or 

creeping. The electric winch adds a 
safety feature in eliminating spinning 
handles, slipping clutches or exposed 
gears. 




, CJ 



The TDD- 1 00 Winch is driven by 
the average 3/8 in. drill. Two drive 
bits are furnished with the winch to 
be inserted into the gear train for 
raising and lowering. If the drill is not 
reversible, the short drive bit can be 
inserted in the opposite end of the 
winch to lower the load. Braking is 
automatic and the TDD- 1 00, stopped 
at any point, will hold a load indefi- 
nitely. 

Both winches are easily installed 
and bolt directly onto the existing 
tower winch mounting frame. For 
complete information on the new 
Electric Winches, write Tri-Ex Tower 

Corporation* 7182 Rasmussen Ave., 
VisaliaCA 93277. 



HAND-HELD SSB 

If you do not want to go FM, here's 
a hand unit for the low band enthus- 
iast, single sideband at that The Mini- 
Mi iter II is a crystal controlled rig that 
runs four watts PEP output into a 
fifty to seventy-two ohm load. The 
beauty of this unit is that a short whip 
antenna is available as an accessory 
and the unit is instantly portable for 
field day, emergency, or camping, or 
just having fun sitting under the sun in 
your back yard. The power level is 
adequate for medium range QSOs 
when the kilowatts are not on top of 
you, but that's the fun of QRP opera- 

(com. on page $ J 



More New Products 

(continued from page 7) 
tion. The Mini-Mitter is available as a 
kit for $150, Popular frequencies of 
3^95, 721 5, or 7255 are available, and 
the rig can be changed according to 
instructions in the manual. For com- 
plete information, write to American 
States Electronics, J 074 Wentwvrth 
St,. Mountain View CA 94040, 

MINIATURE BUZZER 

Miniature is the word, too . . . 
7/8" long. 5/8" wide, and J/8" thick 
is small. The output is good and loud, 
though, despite its small size to per* 
mit it to be used for code practice for 
a good sized room full of people. The 
buzzer is available in L5 and 12 volt 
dc models, with the 12-volt unit draw- 
ing only 15 mA, quite low enough to 
be operated by a transistor gate for 
paging or warning applications. The 
quarter ounce unit is small and light 
enough for uses in hand transceivers. 

The Model GA-100 buzzer is solid 
state and has no moving contacts, 
therefore there is no arcing and no 
electrical or rf noise generated as with 
most buzzer units which act as minia- 
ture spark transmitters. 

The output tone runs around 400 
[[/., ahoul right lor code practice or 
paging uses. 

The buzzer is being marketed by 
Projects Unlimited, Box 1426 North- 
ridge, Dayton OH 454 14 \ and sells for 
$5.95 through parts distributors. 

MINIATURE TONE ENCODER 




Alpha Electronic Services Inc. has 
announced its new hybrid tone en- 
coder Model ST-85J which is designed 
for use in all two-way radio communi- 
cation equipment including portable 
and hand helll units. This compact, 
easily installed unit provides an econ- 
omical method of controlling base 
stations, repeater stations or special 
functions. Current requirement is k 
than 4 mA at 12.6V, Composed of 
two thick film chips, one containing 
the encoder circuitry and one contain- 
ing the frequency determining net- 
work, the ST-85J is available with 
several installation kits and simple 
step- by -step instructions to assure 
easy installation in any make or model 
of radio, especially where space is a 
premium. For additional information, 
write Alpha Electronic Services. im\. 
8431 Monroe Avenue, Stanton CA 
90680, 




SSB TRANSCEIVER 

You can be top man on any band 
with Sideband Engineers* SSB trans- 
ceiver. This rig offers six digit fre- 
quency readout on all bands eighty 
through ten; that's 100 Hz direct 
reading, and the vfo skirt is calibrated 
so you can reset your rig to precisely 
the same frequency time after time. 
But that's not all. The 500 watt PEP 
input is sufficient for barefoot opera- 
tion, and for those who want to run 
the full legal limit, a two kilowatt 
linear amplifier will soon be available. 
The SB-36 has a built in VOX, semi 
break -in CW, and separate crystal lat- 
tice filters for upper and lower side- 
band. These filters allow the rig to 
produce clean and crisp SSB audio 
without frequency shift when chan^ 
ing sidebands. (Ever try to work some- 
one on LSB on forty in the evening? 
Try USB for a pleasant surprise.) 
Accessories include an external vfo for 
split frequency operation and a CW 
receiving filter to help you pick out 
the rare ones from the QRM For 
more information on this amazing rig, 
write to Linear Systems inc., 220 
Airport Boulevard, Watsonville CA 
95076. 

SUBMINIATURE TOOL SET 




Tiny multi-purpose instrument 
tools in a 2 2 -piece set are now avail- 
able for use on very small fasteners. 
Suitable lor use by instrument repair- 
men and hobbyists the tools are de- 
signed for instrument repair and light 
assembly work involving very small 
nuts, set screws, and machine screws. 

The tool set, Mini Kit No. 54, 
contains six jeweler's type screw- 
drivers, two cross-recessed Phillips- 
type drivers, live open-end wrenches. 
three Allen-hex type wrenches, five 
socket wrenches, a marking scribe, 
and a knurled, chuck -type handle for 
positive gripping. The blades are inter- 
changeable, and all are made of hard- 
ened, tempered nickel-plated tool 
steel. The complete set is packaged in 
a clear plastic box for easy use and 
convenient storage. It is priced at 
S 14,50, postage paid. 

For further information, contact 
Jensen 'Putts and Alloys, 4117 \ 
44th St.. Phoenix AZ 85018, 




Dear Sirs: 

I have been trying to receive DX 
stations and stations on the West 
Coast. However, I have not had very 
much luck. Please tell me the times 
during which I can work these sta- 
tions, and the bands where they 
usually are found. 1 would appreciate 
it very much. 

Sincerely, 

Roger W. Miller WNIOGZ 

Bantam CT 
Dear Roger, 

Well I guess you have found that it 
really takes a lot of digging to get the 
DX. Although I am not as much a 
DXer as some, let me share some hints 
I have worked out and a few of those 
from people more successful than I. 

First T listen a lot. There's an old 
adage that says God gave us one 
mouth and two ears to be used in that 
ratio. It's good advice. Very few DX 
stations will come back to long CQs, 
and the rare ones usually do not come 
back to me then I call CQ DX. That is 
what I have found. Listen a lot in the 
General portions of the bands to get 
an idea about what frequencies are 
most active and open. Use a good 
receiver with a good antenna; a ten 
foot long-wire just will not make it for 
consistently good results. A set of 
earphones is a good investment, 
especially if you intend to do any late 
night listening, and even more im- 
portant if your shack is in your 
bedroom, 

Second, choose your frequency 
carefully. Fifteen seems to be going 
out and forty and eighty are coming 
in due to the changing sunspot cycle. 
Now that the sun is sending out less 
radiation that ionizes our atmosphere, 
higher frequency signals (e.g.. fifteen 
meters) are not being reflected to 
distant locations. The last time the 
sunspots changed around like they are 

doing now (they work in eleven year 
cycles), I found that winter months 
meant forty was my best band. A 
friend of mine consistently worked 
Russians on eighty. A second friend 
used to listen intently on ten meters 
for the freak band opening and he 
worked Africans. It is only fair to tell 
you that all of this was in the early 
morning, around six or seven. Others I 
know preferred the late, late night, 
after the TV stations closed down 
Their results were similar. By the way, 
my best direction was South America, 
At night, you have probably found 
that it is extremely hard to pick out 
another ham on the forty meter band. 
It seems that foreign broadcast st 



8 



[SOCIAL/^ 
/■ EVENTS f 

CONTESTS 



VERMONT QSO PARTY 

AH amateurs are invited to partici- 
pate in the Vermont QSO Party spon- 
sored by the Central Vermont Ama- 
teur Radio Club. Vermonters are 
urged to work as many out-of-state 
stations as possible so that those 
interested can earn credit toward 
WAS, WANE, W-VT and USA-CA 
Awards. 

1. TIME: Saturday, Feb. 26, 2300 
GMT (6 P.M. EST) to Monday, Feb. 
28, 0300 GMT ( ] P.M. Sunday) 

2. SCORING: 

Vermont stations 1 point per con- 
tact and multiply by the number of 
ARRL sections and foreign countries 
worked. 

Outside stations 3 points per Ver- 
mont station worked and multiply 
total by the number of Vermont 
counties worked on each band. 

QSO credit with the same station 



tions clutter up the whole place. It is 
true that much of this is illegal opera- 
tion on the part of other nations, but 
the spread of 7.0 MHz to 7.3 MHz is 
not exclusively ham throughout the 
world. Some countries are broadcast- 
ing legally in that range because it is 
legal for them to do so in their part of 
the world. They too are supposed to 
abide by the rule that they should 
cause no interference to other ser- 
vices. But that doesn't help us very 
much at all. I'm going to guess and say 
you go to school. If so, get up an hour 
earlier (that means going to bed 
earlier: don't I sound like your 
parents?). Get up and listen on forty 
or eight to hear what is on. It's often 
different from the night. Try three in 
the morning for more variety. Get the 
picture? The fewer people there are to 
crowd the band, the easier it will be to 
work the few who are there. 

What I'm getting at is to listen 
around the bands and find what is 
best for you; time, frequency, direc- 
tion the antenna works best, the 
weather. 

As to transmitting, they'll rarely 
hear you if you are in the middle of 
the band. It seems like every Novice 
has crystals for the middle of the band 
and uses them all the time. Get closer 
to the band edges. The closer you can 
get to the station you want, the more 
likely he is to hear you. This is a good 
case for owning many crystals. "Im- 
possible", you say. "Even if the price 
were halved.' MicroComm makes a 



on different bands and/or modes will 
be given. 

3. AWARDS: 

(A) Certificates will be awarded to the 
highest scoring stations in each ARRL 
section. 

(B) To the highest scoring station 
outside of Vermont, a trophy will be 
awarded. 

__■ 

(C) To the highest scoring station in 
Vermont, a trophy will be awarded. 

(D) To the 2nd, 3rd, and 4th highest 
scoring stations in Vermont a special 
certificate will be awarded. 

(E) The W-VT (Worked Vermont) 
Certificate will be awarded to stations 
working 13 out of Vermont's 14 
counties, provided the station has not 
previously been issued this award. 

(F) Special certificate for multi- 
-operator stations. 

4. EXCHANGE: Vermont stations 
send number of QSO, RS(T), and 
county. Others send QSO number, 
RS(T) and ARRL section. 

5. GENERAL CALL: For non- 
-Vermont stations: "CQ VT" or "CQ 
VT QSO Party". For Vermont sta- 
tions 4£ DE VT" or "Vermont Calling". 

6. LOGS (or facsimiles): Post- 
marked no later than March 31 should 
be sent to CVARC care Ansel R. 
Carnahan, P.O, Box 3, Montpelier VT 
05602. 

7. Stations sending a S-A.S.E. will 
receive a copy of the results, 

Vermont stations are urged to be 
active and to promptly QSL all sta- 
tions worked. 

'zf "?z w 

The Fifth Annual OOTC QSO Party 
will be held from Tuesday, March 14 
through Thursday, March 16, starting 
and ending times both 2300 GMT. 
Scoring for Canadian and U.S. ama- 
teurs is one point per contact per 



variable crystal oscillator that is like a 
VFO; it allows you to swoosh right on 
top of the station you want to call. Of 
course all swooshing is done with the 
transmitter in standby. They advertise 
in 73, and they only ask forty dollars 
for the device. That's the price of 
about ten crystals and this unit works 
on eighty and forty. A worthwhile 
investment, Fd say. 

As you listen and work around, 
you'll notice that the bands can 
change right out from under you. 
Learn what times the west coast 
comes in. What time does South 
America roll in? Does the band change 
its direction in a clockwise or counter- 
clockwise rotation? Make graphs or 
notes in your log so you will be able 
to tell just what the bands were like 
when you look through your log 
thirty years from now. 

The key is keen listening. If you 
can't hear them s you can't work them. 

73, 
Eric 



band. Contacts with stations outside 
of U.S. and Canada count three points 
per contact per band (KH6 and KL7 
count as DX). Foreign stations earn 
one point per contact per band for 
QSOs within their own country. Five 
points are earned for contacts outside 
of their own country. All modes are 
allowed, but only one contact per 
station per band may be scored. Multi- 
pliers: Count each state, province, or 
country as one multiplier per band 
(DC is counted as a state). Logs must 
be in GMT, and sent to G. Mac- 
Conomy, W6BUK, Space 45, 36770 
Florida Ave,, Hemet CA 92343 no 
later than April 20. 



* 



■Jv 



v-" 



On March 5, the Tri-County AjlC 
will hold its Mid-Winter SwapFest at 
the National Guard Armory in White- 
water WI. The all-day affair will be 
held indoors and there will be lots of 
free parking. Tickets are one dollar in 
advance or one- fifty at the door (an 
extra buck reserves a display table). 
Talk -in will be on 3985 kHz. Contact 
WB9DWG, for tickets and info. His 
address is RR #4, Box 235, Fort 
Atkinson WI 53538. Snow-date is 
March 12. 




(From the West Coast DX Bulletin) 
If construction of a weather station 
on the island of Bouvet proceeds as 
hoped, the call prefix 3Y0 may be 
heard. A ZS1 is being mentioned as 
the one who will be the operator 
there. The Spratley Island expedition 
was not carried through due to unfav- 
orable landing conditions. It appears 
that -the ITU never authorized the use 
of the call 1S1A and prefers that it 
not be appropriated , It has been indi- 
cated that in such instances where 
there is no proper call sign that just 
the call of the operator with the 
geographical location as a suffix 
should be* given. In this instance, the 
call might have been WA5VTU/ 
Spratley, 

From the Pacific area, the Fijis may 
change their VR2 prefix for a 3D2, 
and it seems there is a 3D2 being 
heard on 20. From Nauru, the C20 
prefix may only be used on holidays, 
such as January first. Does anybody 
know when holidays occur on Nauru? 
JD6 will be the prefix for Okinawa to 
replace the KR8 issued by the vacat- 
ing authorities, KJ6BZ, on most days 
at 21,285 at 22O0Z, has been looking 
(continued on page 10) 



9 



DX FOOTNOTES 

(continued from page 9) 

for the Midwest and East Coast. He 
will return to Johnston on March 2. 
VR5FX is stij] very active from 
Tonga, usually found on 20 CW in the 
14,235 to 14,250 kHz range. 

Watch for Karl, VE8RA, as he plans 
to operate from Wall is (FW8) from 
March 14-22, and New Caledonia 
(FK8) from March 22-27, possibly 
until April 3 depending on activity- 
All bands will be used from each 
location. When calling, indicate 
whether you are transcelve. Karl will 
also listen in the General portions of 
the bands and QSLs will be handled 
by VE7BWG. 

From a remote plantation in Haiti, 
HH9DL has been heard at 14,220 kHz 
around 2250Z. Don, the only true 
HH9 in residence, is also reported as 
showing up regularly on forty at 7250 
kHz at I230-1300Z. His QTH is at 
Fort Liberte. thirty miles west of Cap 
Haitian. 

SUIIM and his daughter Dr. 
Moon a, SIMM I, are the only 
Egyptians currently active, Ibrahim 
has been trying to get through to the 
West Coast around I500Z and after, 
usually operating in the 
14,040-14,060 slot. K6KA has an 
eyeball sked with SUIIM in Cairo this 
April. Hopefully they'll make it. 

And from the Far East, A5A to 
A5Z has been assigned to Bhutan. 
Yontan's SSB signal was last reported 
as not too strong. He may try the 
1600 1700 time period on CW look- 
ing for the 6"s and 7*$, Look for him 
around 14,045, but he was recently 
heard at 14,301 at I200Z. 

An ARRL Directors' Letter informs 
us that a third party agreement has 
been signed between Trinidad and 
Tobago and the United States. Since 
this is the first instance of "British" 
willingness to allow its amateurs to 
handle third party traffic, hopefully it 
is a portent of similar things to come, 



DX NEWS 

If a direct QSL address is not 
otherwise available, QSL's for K and 
W/TF amateurs operating in Iceland 
should be sent to Keflavik Amateur 
Radio Organization, Box 44, FPO 
New York NY 0957 1. 

Box 1058 Reykjavik is appropriate 
for QSLmg to Icelandic nationals 
(TF--)only. 



Tell our 

Advertisers 

You Saw it 

in 73 



%u? Jfo Jk 




I have been very pleased with the 
good service in changing my address 
and getting me my 73 magazines. I 
subscribe to two other electronic mag- 
azines, and yours is the only one I 
have been receiving since I came to 
N.Z. four months ago, 

Ham radio oyer here is a little 
different. These guys are homebrew 
artists! They are known as "Make-do"* 
artists and it is certainly true! I feel 
conspicuous with all my factory-built 
gear, and will have to start building 
again. There is a spirit among the 
hams and at radio club meetings that I 
remember in the states back in the 
30's . . , friendliness and "shirt off my 
back" attitudes, etc. They have cer- 
tainly been most helpful to me. I 
obtained my reciprocal call with a 
minimum of red tape and now have 
K4IF/ZL1BME for a call I will sit the 
regular exam and then will have just a 
ZL call, (This because I have immi- 
grated permanently .) 

H. D. Wocrtendyke 
Blenheim NZ 



I have my end of the ten meter link 
in operation and tied into my remote 
on Harness Mountain. As it now 
stands, 94 signals heard on my 
mountain are retransmitted on 29.680 
and incoming signals are retransmitted 
out on 34. Subject, of course, to my 
control. Anyone listening on 29.680 
will hear the Pacific Northwest repeat- 
ers along with the "auto-ID." This 
auto ID consists of a female sexy 
voice who every 3 minutes says: 'This 
is the W7DXX DX repeater on Har- 
ness Mountain in southern Oregon/ 
When the repeater (the 10 meter end) 
is activated from another 10 meter 
signal the auto ID sends a CW ID (de 
W7DXX/DX RPT). 

Until you get your end going or 
someone who reads your comments in 
this month's 73 gets his going on 
29.680 there will be no DX. However, 
anyone with receive capabilities 
should hear the Pacific Northwest 
when 10 is open. 

If you wish, give me a call on SSB 
on 10 and we can coordinate. You 
pick the frequency and time. 

Take a listen to 29.680 for the link 
and let me know when you are ready 
to go. 

Keith E. Lamoniea W7DXX 

Springfield OR 

Keith's repeater expaLs the range 
of the two meter enthusiast many 
hundreds of times. Can you envision 
coast-to-coast contacts with a little 
hand-held unit with a nineteen-inch 
whip? Think of it. 



you print ev 



Having tried many times to learn 
the code and get a ticket I read with 
interest WB6JN1 article that each let- 
ter should be sent at about 20 wpm. 
W3KBM also made a similar editorial 
Nov, 1970. Once I had such a code 
instructor and it helped but he was 
only substituting. 

Could you tell me if any code 
"tapes" are available that are "skip" 
recorded? If none are available maybe 
a reader would be able to make me a 
"skip" tape of K9AAU "A New Sys- 
tem for Learning Morse Code" Apr, 
1969. 

Ramer W. Slreed 
3004 So, West Avenue 
Sioux Falls SD 57105 

Off-hand t we don*t know of any 
such tapes, Perhaps one of our readers 
can help out here. -E. 

I would like to apply for your Real 
Rag Chewers Award. 1 have completed 
the requirements set forth in your 
Sept. L 71 issue. 

The calls of the stations involved. 
WB9EMV (me) and WB9CKG The 
operators 1 names are WB9EMV Mark 
Miller, and WB9CKG Richard 
Leiterman, The times were from 2300 
GMT, December 21st, to 0500 GMT, 
December 22, We used the 40 meter 
band with the modes of CW, SSB, 
AM. 

I have been a subscriber to 73 ever 
since I was a beginning Novice (my 
only ham mag.). I enjoy it very much 
and am glad you came out with these 
fine awards for us without big beams 
or kilowatts. 

Mark Miller 
Wauwatosa WI 



Other awards available are the 
WAZP (Worked All Zones Promised). 
This is a pledge to do just that - a 
promise to work all 40 zones. The 
Certificate Haters Club is a solemn 
oath to hate this and any other 
certificates that might ever be earned. 
Less tongue-in-cheek awards that 
recognize real operating accomplish- 
ments include the WAAS. Worked 
Almost All States, Everyone knows 
that the fiftieth state is the hardest to 
work, and this award recognizes the 
achievement of 9$% of the intended 
goal. And an easy chore for the DXer 
might he to work ten countries, but 
the Novice (and some Generals too) 
has to really work hard to get thai 
many. The DX Decade Club is a large 
group of DXers who do not make 
DXing their chief aim Endorsements 
are available too. To receive the CMC 
or WAZP. send a signed statement 



10 



swearing to abide by the appropriate 
conditions. For RRCQ send the calls 
of the stations involved, names of the 
ops, and times (GMT) beginning and 
ending the QSQ. For DXDC and 
WAAS, send the QSLs (package them 
carefully and include return postage 
sufficient for first class mail) so we 
can send them back to you. Naturally, 
all awards cost one dollar and you can 
send for them in care of the Novice 
Editor, 73 Magazine. Peterborough 
NH 03458. 

Well you finally found a type size 
so small that it cannot be read. 1 refer 
to the lack of an index for the year of 
1*971. Only you would print the 
December issue without the yearly 
index. 

W.C. WarmatiWlKVK 
S. Burlington VT 

The yearly index wm postponed hecdum we ere 
planning a complete index from October I960 to 
December 1971. All in due time. 

EHc 

Here s my $6 for another year. I 
think 73 is the best by far of all the 
ham magazines. I enjoy it very much 
and really look forward to the next 
issue each month. 

Another note is on the ads in 73, 1 
really enjoy reading the ads and I like 
them spread throughout the magazine. 
Your ads just seem to be more attrac- 
tive than in the other magazines and I 
make a point to read all of them. I 
really like the color ads and especially 
liked the Regency ad in October, 

So keep up the good work and 
when all the other magazines are gone 
73 will still be on top in my book, 

Larry Standlee WA5NTF 

Our faces are blushing. 

I just got my Dec. issue of 73 (my 3 
year renewal was just sent in), Like 
you, I was disappointed in the Dec. 
issfie, I sure hope you get ads to build 
up 73, also more good articles. 

More power from 6146 was a dis- 
appointment to me. It's like taking a 
stock car designed for average 60-65 
mph and driving it 95-100 way past 
design. I like to run things with 
reserve. 

On the subject of interesting QSOs 
I hardly even run into anyone I wish 
to sign with quickly. Most of them I 
look forward to talking to again, I just 
don't get on as much as 1 would like. 

Orville Gulseth W5PGG 
Clark ad ale MS 

Several months back I bought a 
copy of your "Amateur Radio Extra* 
Class License Study Guide.** After 
which time I practically lived with it 
until taking the Extra examination 
November 16. Upon completion of it 
I was told I "almost*" passed it, 
meaning 1 didn't. Back to the drawing 
board and the study guide and a 
return bout on December 14 which 
proved an overwhelming success, and 
believe me, I owe 95% of it to you 
and your genius (genii?) minds for 
compiling and publishing such a help- 
ful Study Guide. It is most compre- 



hensive in scope and information ob- 
tained from it enabled me to under- 
stand subject matter that had hitherto 
been way over my head. 

My first try at the examination, and 
failure, was by no means the fault of 
the Study Guide. I just had not had 
enough practical experience with a lot 
of the subject matter to envision the 
answers they wanted. The examina- 
tion showed me where I had spent a 
lot of time studying subjects that they 
weren't interested in and by the same 
token showed me what to expect the 
second time around. 

In general, this is to write my 
appreciation for making this hook 
available to Hamdon, which has been 
sorely in need of something like this. 
It will surely remain a valuable item in 
my library and I hope other hams feel 
the same. Without reservation, the 
genius who put this Guide together 
has no equal, "par excellence!* 

RossE. Hicks, Jr. W5LPF 
Arlington TX 76010 

You re welcome, you're welcome. 
This letter is typical of those we 
receive in reference to our Study 
Guides — Novice, General, Advanced, 
and Extra. 

1 have received about 100 letters 
from readers on the Tlugin Solid- 
State Vibrator Eliminator" which you 
have reprinted in the Jan, 72 issue. 
Most of them ask for additional infor- 
mation and errors if any. Here are the 
most common questions and answers. 

The original circuit shows resistors 
Rl and R2 and being 44 and 4.4Q. 
(A) This was a printing error and 
should read 4.4n each. However the 
value required may be between 3.3 to 
5fi. 

What type transistors did you use? 
(A> I used Two type 2N443 stud style 
transistors. 

Is there an American replacement 
for the toroid? (A) To my knowledge 
there is no American replacement. 
The Hammond Model 51 IE is manu- 
factured in Canada by the Hammond 
Manufacturing Company, Guelph, 
Ontario. H owever it cannot be pur- 
chased direct but through most of the 
electronic jobbers here. 

Do you recommend any other 
changes? (A) I would install a choke 
and filter in the 12 volt line to prevent 
the 200 Hz from getting out on 12 
volt line. 

Since there, are probably many 
more readers who might be interested > 
1 have sent this info which should be 
helpful. 

Vem Epp VE7ABK 
Nelson BC 

I echo your plea for an article on a 
synthesizer. 1 am amazed that some of 
the leaders in solid state devices and 
accessories haven't seen the need that 
exists* How about a nice kit? Also 
how about an article on adding a 
limiter/discriminator/squelch to AM 
receivers? Take your old communica- 
tions receiver, hang an FM receiving 
adapter on it next to a converter, wire 



a meter in the discriminator and may- 
be even a deviation meter, and you 
have a highly useful instrument that 
can do quadruple duty. 

I'm not smart enough to design 
these things, but I sure can see a need 
for them. 

Re your suggestion on a repeater 
contest. Sometimes you have good 
ideas. This time you didn't. A contest 
would not be in keeping with the type 
of operation mo>t repeater users 
desire, I love contest work, but not 
the screaming and backstabbing that 
would go on for the inputs of the 
machines. 

Frank J. Derfler Jr, K9KIC/1 



I have been a licensed amateur for 
13 years, an ARRL member for the 
last six consecutive years (I had to 
join because I could not longer buy 
the QST over the counter). I have 
been an IEEE member going on my 
third year. So you see 1 do know 
something about both organizations. 

I agree with Mr. Chapin in his Guest 
Editorial in Jan. 1972 issue of 73, I 
too feel there is a need to reorganize 
the organizational structure of the 
ARRL and update the by-laws and 
constitution using the IEEE as a pat- 
tern* 

In Mr. Chapin's editorial only four 
classes of membership in the IEEE 
were listed , but there are five grades 
of membership. The associate member 
grade was not listed. The grades of 
membership in the IEEE are (1) Fel- 
low — (2) Senior Member - (3) 
Member - (4) Associate and (5) Stu- 
dent. 

Frederick R. Washburn WA6FJJ 

Los Angeles CA 

About two months ago I bought a 
Tempo One w/ac supply from Henry 
Radio in L.A, In the order I pointed 
out that my decision was based solely 
on an ad in 73 Mag. 

I like this rig. I had not planned a 
purchase of this size this year, but the 
family has grown and left home so 
funds are available. 

This is my first SSB transceiver. So 
with limited background and exper- 
ience in this area, 1 still like it. Using 
dipoles, if I can hear them, I can work 
them. 

The other night at 7.25 1 MHz there 
was a fellow in Ecuador working a 
U.S. station. Guess what happened? 
One of our friendly, courteous hams 
loads up right on freq; 1st the xmttr, 
then the linear. He wiped out every- 
thing. Why can't these people load up 
a few kHz away and then come on 

fre( l ? R. W. Yerbmy 

Dugway uf 

For ten dollars, a person can obtain 
a dummy load and use it. This would 
end the headaches of thousands of 
hams who listen and complain of 
QRM. It would also keep them from 
being headaches. 

E 

(continued on page 12) 



11 



LETTERS cont 



Tnx for making the DXDC award 
available; now I have something to 
shoot for. The following list shows 
what DX Fve worked, and in what 
order: VE, KL7, JR. LU, OH. TL 
KOk XE, KH6, KZ5, KV4, ZL, VK. 
KG6, PJ° ? and UK0 . The last 4 were 
in the DX contest (CW, of course). 
Please don't lose these cards, because I 
already feel sick about giving them to 
the post office, hi! 

Urry Des Jardin WB6KMW 
San Andreas CA 

The P.O. got them here all right. 
They are pretty dependable. The 
DXDC award is available to all who 
send proof of two-way QSO's with ten 
or more foreign countries (and a buck 
and return postage}. Novices, es- 
pecially might be interested in this 
award. 

My recent QSO with W2NSD 
Mobile 146.94 direct on 1/3/72 has 
led me to look into 73 magazine. I 
discovered a magazine I thoroughly 
enjoy, just as much as talking to 
Wayne, 

Doitn Watson WA2REH/1 

Boston MA 

You would be interested to know 
how other Ham publications are rated 
in this country, I have recently ac- 
quired a set of CQ for 1970 and could 
not find a single useful article. The 
RTTY column, which used to be one 
of their regular features, is gone, and 
there is little else of interest to us in 
India, The U.S. Library here donated 
to our club a set of QST for 1970. 
This bunch had a few articles of 
interest, but nothing comparable to 
the articles you run. You might like to 
know that while no one at Madras 
subscribes to CQ or QST, my copy of 
73 is read by no less than 4 ham 
families, three of which contain two 
ticket-holders, in effect a readership 
of seven. 

Let me wish you a bright and 
prosperous 1972. 

M. V, Chauhan 
Madras* India 

Just had an idea for a ten -minute 
timer when my daughter's alarm clock 
broke and I was asked to repair it. 
Being a ham I noticed the SNOOZE 
ALARM lasted ten minutes. After five 
years of thinking, actually about three 
seconds, it occurred to me that this 
would make a perfect ten minute 
alarm for the ham to announce his call 
and how can you beat that for S2.98, 

All that has to be done is disable 
the regular 1 2-hour alarm (simple 
upon examination) and whenever you 
want the ten-minute timer to work, 
just pull out the alarm se* lever and 
push down the Snooze button. Ten 
minutes later the thing can blow up 



Boulder Dam, turn on your tape 
recorder, announcing a station break 
and your call letters. If you don't hit 
the Snooze button pretty soon it will 
start th^ first bars of "Dixie'* and end 
up with "Who Got My Roller Skates." 
At least it will go off every ten 
minutes every time you hit the 
Snooze button. 

You can buy a lot of beer or even a 
vari-coupler and a 20 1 A for the 
money you save while making the 
FCC happy. 

Clyde A* Welch WA4VKB 

Anderson SC 



Amateur radio allows a wide variety 
of operating methods and activities, 
but there is one type of operation I 
would like to engage in but cannot - I 
would like to talk to my wife while I 
am driving around in the car. Since 
the chances of her ever getting a 
license are pretty slim, the best solu- 
tion seems to be either CB or a 
repeater with autopatch. 

However, after reading the section 
of your editorial in the January issue 
about the advantages of using duplex 
on 220 MHz, another possibility has 
occurred to me. Why not remotely 
control the home station with the 
mobile transmitter? Then the xyl 
could talk through the home station. 

This could be accomplished very 
easily if duplex were used. A low 
frequency remote control signal could 
be transmitted from the mobile along 
with the voice transmission to simul- 
taneously turn on the home transmit- 
ter, activate the station identification 
circuits and signal the xyl. Each user 
of the system would have a different 
remote control signal. 

The xyl would operate a micro- 
phone switch that would control the 
modulation of the carrier. This would 
comply with the rules since they 
require that only the carrier be turned 
on and off by a licensed operator. The 
station would be identified auto- 
matically in a manner similar to that 
used by repeaters. 

Full duplex is not required. The 
repeater would have two separate re- 
ceivers, but the combined receiver 
outputs could modulate only one 
transmitter. This would reduce the 
complexity and expense of the system 
and still allow one person to break the 
other. Most of the time, only one 
person will be talking at a time any- 
way. Another advantage is that calling 
will be simplified since everyone will 
be listening to the same frequency. 

I don't see anything illegal about 
remotely controlling the home trans- 
mitter and operating it in this manner. 
The main FCC problem would seem 
to be in obtaining permission to re- 
motely control the home station from 
the mobile. 

I wonder if other readers think this 
type of operation is legal, possible and 
practical. 

Roy E, Gould W5PAG 

4748 DeBeers Drive 

El Paso TX 79924 



Note in the latest Callbook that 
New Hampshire is dropping in ham 
population as is the general count. 
Hmmra 

Missed the Revoked License box in 
the last issue. Watch the FCC releases 
for a bunch from the west coast. 
Some of them have been jamming 
WCARS and other communications 
on 40 and 80, and who knows what 
all else. One of them said he'd be on 
the air Oust far enough away to 
splatter on the freq) until someone 
came by and took his ticket off the 
wall. Looks like somebody did! They 
nabbed a kid in Vegas who threatened 
to fight the president of the net if he 
showed up in town; as well as the 
goon who sounded like a pig. 

Paul Schuett WA6CPP 

Lodi CA 

Hallelujah! Congratulations to 
those who helped rid the air of some 
inconsiderate ones. Every day we get 
letters about noise, QRM t and inten- 
tional jamming. It may seem like the 
Golden Rule is outdared and we need 
force to accomplish the same goals, 

Bfit for each bad news letter, we get 
ten like the following; 

Fer the skinny blonde wat sends 
them 4 elp notes from the dunjun* 
Don't wurry Luv, 'elp is on the way. I 
just give yore boss sum munny fer 
that pitchur mikin' book so I can git 
mi camera going like 'airy Bloggs. 'E 
blots out chanel 24 and 14 an I wont 
sum too so pik we out a good wun 
and if there's any left over send me 
some of them Mat Dillons an Festuses 
u got in the cellar. Tell yore boss *es 
got a gud thing goin fur us 'ams wot 
can reed an rite an make things. So 
don't sen enymore of them 'elp notes. 
My old lady don't like it and sets the 
dorg to bitin" me w'ere I use most fer 
oporatin' my geer w'en it's in vox. An 
my cher don't 'ave no cushin. An tell 
Big Ears * e ort to go fer ARL direktur 
an git us sum sence out of Charlie 
wots givin* away our bands. Don't 
fergit to send mi TV book kwik. 

WA8QXIJ 

Any activity on 10 meters FM? 
What does FCC think of 2 meters to 
10 meter repeaters (or vice versa?) 
Anyone trying it successfully? 

Barry FooteKlBTF 
Framingham MA 

Yes, there is quite a bit of activity 
on 29.6 MHz, particularly with low 
power rigs. On 29.68 MHz there are a 
growing number of repeater links to 
two meters. W7DXX seems to be 
pioneering this a though other repeater 
groups are reported getting into the 
action. Look for WAIKGS in 
Walt ham to be linked to 29.68 
soon . . . and others. It won't be long 
before two meter groups will be in 
contact with each other via 29.68 
links . . . and* as W7DXX asks, how 
long will it be before someone driving 
in San Diego is talking with someone 
in Munich? Not long! DXX has al- 
ready been pioneering some 20m links 
and recently the two meter gang had a 
chance to work UA0ZAR via the 
repeater. 



12 



Due to my future husband, 
WA4GPJ, [ have become an avid fan 
of 73 and amateur radio I really 
enjoy 73 and although I don't under- 
stand all the technical articles, some 
of them are actually sinking in! 

I have copies of every 73 from 
August 1970 through September 1971 
in which you published a series of 
articles on the General Class License, 
Unfortunately I don't have a copy of 
July 1970 which contains the begin- 
ning article. Is there any possibility of 
getting a copy of General Class 
License Part I? The articles are well 
done and the progress is logical and 
simple. So many of the License 
Guides assume that one knows a lot of 
technical knowledge. 

It won id also be great if you could 
print articles for XYL's who could 
enjoy their husbands hobby instead of 
being a "Ham widow/* I am delighted 
that Jerry is urging me to get my ham 
license. In fact, for Christmas he gave 
me a code key and a code oscillator, 
all rigged up and ready for me to 
operate. What more unusual Christmas 
gift could a future XYL get? By the 
way, I found the code very easy, 
considering the fear I had before 
getting started on it. Could you com- 
pare it to going to the dentist - "The 
I-know-i t-isi;o in g- to-hurt bit?" 

Again, I really enjoy 73 and es- 
pecially your editorials and humor 
that appears in the oddest places. You 
might say 1 think that 73 is terrific. 

Ann Large nt 
Richmond VA 

Ann, all the best to you and Jerry. 
Your missing copy is on* the way with 
our blessings. The number of YL and 
XYL articles we print is about propor- 
tionate to the number we receive; 
maybe you will share with us your 
experiences after the big day. By the 
way, I read of another ham who gave 
his fiancee a code practice oscillator in 
kit form and made her build it in 
front of him. In comparison, Jerry 
sounds tike a pretty good guy. 

I reread your December editorial 
for the second time after letting it 
sink in for a couple of weeks or so* 

I guess you could consider me a 
DX'er of sorts, or a rag chewer of 
sorts, or one who really cares about 
the chap on the other end. thousands 
of miles away. I have confirmations 
for DXCC at 241 and 1 don't really 
feel it is all that important to get 242 
unless it comes easily. 

1 have operated from "CTl" and 1 
also hold G5AUP in U.K. When I'm in 
this country I like to work the boys in 
Europe and around the world. When 
in Europe I like to work back this 
way, It's nice to work Father Moran 
(9N1MN) from NJ, but it's fun shak- 
ing him up from my London location, 
too. Why? Because he is concerned; he 
remembers about you, your friends, 
etc. Something personal, you see, is 

the key. 

You won't get rid of the phone- 
patch gentlemen in the rare DX part 



of the band until you educate them as 
well as respect them on their part of 
the band- Sort of a gentleman's agree- 
ment you might way. 

Now let's get down to the real biz 
of making a meaningful QSG, 

It is important to really listen to 
what the other fellow or lass has to 
say. Don't be afraid to comment and 
above all have something to say, not 
just rst, QTH & name. Find out if he 
makes wine for a hobby or watches 
mini skirts. Judging by his accent you 
might ask if he is possibly from a 
different part of the world. What can 
you find in common with the other 
op? Follow this up if it was a good 
chat and make a file card on him. 
Next time ask him how his wife and 
kids are. What a surprise for him that 
you not only knew his name, but you 
knew his family, too, It takes hard 
work to acquire this type of feel for 
things. It will pay off tenfold. I assure 
you. 

I keep track of over 3,000 people 
outside of the USA and I assure you it 
doesn^t take me more than ten sec- 
onds to know my man or woman at 
the other end of the DX band on 
either CW or SSB, lOmor 1 6m. 

1 don't think I have anything spec- 
ial going for me except I don't make it 
a practice of asking for a QSL with 
my first over — Hi, 

The other day I had a 1 hour QSO 
with a 7Q7 on 14.255 MHz. It must 
have been more than a report and 
how's the WX* It must be frustrating 
for a chap who needs 7Q7 and could 
care less about our chatter. But for 
those who were kind enough to stand 
by and not lose their heads, it paid 
off, for this 7Q7 was in a good mood 
then. 

Chances are I will be talking to him 
again soon and by past experience he 
will know where to look for me and 
will probably call me. 

Many amateurs don't know that for 
each working op there may be ten 
listening to your QSO. Some of my 
new-found friends are really old 
friends in a way as some tell me, * 4 I 
listened to you for over two years 
before I got my ticket" or "We like 
what we hear and feel we really know 
you." 

Try to work in and around the 
same frequency from time to time. 
Get to know the people well. Check 
that freq. at least twice before making 
that t4 CQ Europe." They size you up 
quickly and they can cut you down 
just as fast. Try to understand what 
makes people tick. Do the unusual. 
Talk about things not related to radio. 
Ask him about his country and what a 
loaf of bread costs. How many hours 
of work to buy a certain item, and so 
on. In other words, get involved. 
Above all, be sincere, be helpful, 
speak slowly to a chap who has 
trouble with English, Use small words, 
Be patient. 

I assure anyone it works. I have 
skeds with Europe and Africa on a 
regular basis, and I have had visitors 
from Greenland, Denmark, England, 1 

(continued on page 14) 

13 



(SSTV Scene cont. from p. 5 J 

Well, if you are still looking for 
African QSO's listen for ZS3B on 
either 14.230 or 21.340 around 
1900-2100 GMT. ZS6PP also fre- 
quents 21.340, often around 1630 
GMT, EL2BC should be getting his 
Robot gear by now also. Watch for 
him also on 2L340, Generally, the 
Europeans and Africans are leaning 
toward 2 1 ,340 activity with 1 4.230 as 
a secondary choice. Much activity, 
also, from down under (VKS and 
ZLS) but thisll call for the midnight 
oil. They generally show around 
0800-0900 GMT on 14,230 (twenty 
is starting back its "Late Night Re- 
Openings" a little early this year), 

WeVe been 'looking in" lately on 
the Canadian SSTV net, which meets 
on Sundays and 2200 GMT on 1 4 J 80 
kHz. Very good pictures — some real 
candid* shots - and a lot of info ex- 
changed. Look in some Sunday, I 
think you'll like it. 

The year 1972 promises to be an 
outstanding year. The advent of S0i 
integrated circuits, $5 phase-locked 
loop IC's and availability of 12 — 16 
inch P7 phosphor cathode ray tubes, 
should be a real boon to SSTV, 
W0LMD has proven his all integrated 
circuit, magnetically deflected moni- 
tor for over a year now. So it should 
be appearing in print soon. 

If you can't wait, and Sid can't 
furnish you with a diagram, send me 
an SASE and 111 drop you a copy. 
The monitor has bandpass filters and a 
tunable SYNC detector circuit, which 
really proves itself on marginal signals. 
Also, this year, watch for more infor- 
mation on the larger screen monitors, 
slow scanned cameras and new ideas 
on flying spot scanners. And watch 
for Heath to come out with a nice 
monitor for under $250 - maybe an 
SB205. 

The Dayton Hamvention is coming 
up again in late April and, as usual, 
much slow scan activity is planned. 
Many of the new ideas on SSTV were 
first presented at the Dayton conven- 
tion, and Pm sure this year will be no 
exception. Everyone will bring dia- 
grams of their "brainchild 11 to the 
SSTV booth, and many of the top 
SSTV'ers are usually around. 

Possibly Don Miller W9NTP, will 
unveil his SSTV handbook there this 
year. 

The second W.W. SSTV contest 
should be over by the time this 
appears in print, so why not drop a 
postcard to me giving your results and 
score. Results will be tabulated, and 
Til report the new "Big Guns" in this 
column. Send along pix or tapes of 
interest also. Til photograph an inter- 
esting picture or so for possible publi- 
cation in this column later. 

, - .K4TWJ 



Caveat Emptor 



WJ CXi 



U^CVi 



Price — $2 ptt 25 words for non- 
commercial ads; $10 per 25 words for 
business ventures* No display ads or 
afencydUcount. Include your check 
with order* 

Deadline for ads is the 1st of the 
month two months prior to publica- 
tion. For example: January .1st is the 
deadline for the March issue which will 
be mailed on the 10th of February, 

Type copy. Phrase and punctuate 
exactly as you wish it to appear. No 
all- capita I ads. 

We will be the judge of suitability of 
ads. Our responsibility for errors ex* 
tends only to printing a correct ad in a 
later issue. 

For $1 extra we can maintain a reply 
box for you, 

We cannot check into each advertiser, 
so Caveat Emptor. • • 

STANDARD SRC 145, Japanese 
equivalent to the SRC- 1 46 hand-held 
unit for 2m FM With simplex crystals 
for low end of band. First certified 
check for $200 to Box N, 73 Maga- 
zine. 

BALUN-2KW, I;l, with coax fit- 
ting and dipole insulator, Teflon insu- 
lated wire, epoxy encapsulated, $8.95. 
Plate Choke 2A., 5KV, $6.45. Dual 
3QA. shielded filament choke $6.95. 
ppd. ISA. GREGORY KORDI-S. 
Box 1279, Tustin, California 92680, 



(continued from page 13) 
Portugal agd others. I have also done 
the same myself, I assure you that 
when you visit a foreign land and you 
meet your friends they will show you 
and your family things no regular 
American would usually see. 

What amateur in a foreign land 
would put up a 60 ft erankdown, 
tilt-over tower with beam at his coun- 
try place with wall-to-wall American 
gear for my use during my stay? You 
say, he's kidding, Not so — I will show 
doubters color pictures. 

Would you believe a very important 
man in his country took time off from 
his important duties to be a guide for 
my wife and me? 

Could you imagine that a gentle- 
man in one country who said he 
would meet us at the airport sent two 
dozen red roses to our hotel because 
he was called away to HB9 land, but 
another amateur and his wife drove 50 
miles during the night to be there 
waiting with my QSL card in his hand 
so 1 would know someone cared. 

This has only boon a small sample 
of what can happen if you let yourself 
be involved. 

Amateur radio can do more for 
international good will than our State 
Department has over the years. 

Think of it in another way. What 

can I do for amateur radio? How can I 

get involved? Is that QSL all that 

important? (it will come in time, 

anyway.) fc _ _. 

Paul T. Atkins WB20ZW 

Park Ridgp NJ 



ROCHESTER, NX is again Hamfest, 
VHF meet and flea market headquar- 
ters for the largest event in the north 
east. Mav 13th. Write WNY Ham test, 
Box 1388, Rochester, N.Y. [4603. 

HOOSIER ELECTRONICS Your ham 
headquarters in the heart of the Mid- 
west where only the finest amateur 

equipment is sold. Authorized dealers 
for Drake, Hy-Gain, Regency, Ten- 
Tec, Galaxy, Electro- Voice, and 
Shure. All equipment new and fully 
guaranteed. Write today for our low 
quote and try our personal, Triendly 
Hoosier service. Hoosier Electronics, 
Dept, D., R,R. 25, Box 403, Terre 
Haute, Indiana 47802. 

73's - Vol I No I to date. Some 
bound — Some with minor cover 
damage. Best offer within 30 days. 
W3CJY, 6281 Akron St,, Temple 
Hills, Md. 2003 1 , 

B RAND NEW coax connectors 
PI-259 (male) or UG-260D (BNC 
male) 7 for $2,00; nice low impedance 
headphones reconditioned $5,00 each; 
New carbon paper black typewriter 
ribbons for IBM Executive models A, 
B, C SI. 50 dozen. All plus postage. 
Bill Hay ward W0 PEM, 1307 NE 57th 
Terr., Gladstone, Missouri 641 18. 

FCC ^TESTS ANSWERS" 

Original exam manual for First and 
Second Class License. — plus - ** Self- 
Study Ability Test/' Proven! $9.95. 
Satisfaction Guaranteed. Command, 
Box 26348-S, San Francisco 94126. 

7289 (3CX100A5) ceramic sub for 
2C39. Surplus. Pre-checked at 449 
MHz & guaranteed. $3. ea.; $30 doz., 
plus postage. Ed Howell, Folly Beach, 
S.C 29439. 

SELL: Copper clad, both sides, epoxy 
board 3x24x1/16 $1.25, 3x21x1/16 
$1.00, 3x18x3/32 SI. 00 post paid. 
Vernon Fitzpatrick, WA80IK, McLain 
Park, M-203, Hancock, Mich. 49930. 

2 MTR. POWER SUPPLIES 

Solid state. Regulated, overload pro- 
tected 117V AC in/13.5V DC @ 3 
Amp. out. Only $22.95 & 5 LOO 
POSTAGE. Limited Quantity. Low, 
Low Prices on Japanese 2 mtr Gear, 
Free Catalogue, GLENWOOD TRAD- 
ING CO., Box 1009, Blaine, Wa., 
98230. 

TELETYPE: Model 14 typing reperf, 
S28; CV-278/GRC late model FSK 
converter, $105; 40 rolls ll/16 v per- 
forator tape, $8. Jim Cooper. POB 
73-M. Pararnus, NJ 07652. 

DRAKE 2C, Xtal Calb., with 2 CQ 
and Drake 2NT Xmtr. $300.00. Like 
new, Bart Burne, WN3QXU, 1725 
Wyoming Ave., Scranton, PA. 18509. 

YOUR CALL LETTERS, Two sets, 
for windshield and rear glass. Smart 
white letters with red outline. Easily 
installed pressure sensitive decals. 
$1.00, postage paid, anywhere. Satis- 
faction guaranteed. Lake Jordan 
Artists, Slapout AL 36092. 



GREATER BALTIMORE HAM 

ROREE. Sunday April <> at 10 A.M. 
Calvert Hall College, Goucher Blvd. 
and LaSalle Road, Towson, Maryland 
21204 (1 mile south of Exit 28 
BeJtway-lnier^tate 695), Food Ser- 
vice, Prizes, Flea Market, $1.50 Ad- 
mission. NO TABLE CHARGE OR 
PERCENTAGE. 

EVANSVILLE, Indiana HAMFEST 
4H Grounds (Highway 41 North 3 
miles) Sunday, May 7, 1972; air con- 
ditioned, auction, overnight camping, 
ladies' bingo, reserved Ilea market 
booths. Advance Registration. For 
flyer, contact Morton Silverman 
W9GJ, 1121 Bonnie View Drive, 
Evansville, Ind. 47715. 

WANT CLEAN COLLINS 5IJ^4. also 
Drake C-4; with manuals and original 
shipping containers, No junk! First 
letter give each serial number, condi- 
tion, price; also price for both, if have 
both, Watson, 700 West Willow Street, 
Long Beach, CA 90806. 

MOULTRIE Amateur Radio Kluh, 
11th annual Hamfest, Wyman Park, 
Sullivan, Illinois, ~ April 30, 1972, 
Indoor-outdoor market. Ticket dona- 
tion $1.00 in advance - $1,50 at the 
gate. Open 8:30 A.M. 
W9BIL - 146.94 MHz. MARK. Inc. 
P.O. Box 327, Mattoon, Illinois 
61938. 

ROBERTS 50 watt AM/FM Stereo 
Receiver $100 PPD. - Picture. Past 
issues radio magazines wanted! 
Thomas King, 340 Water, Platteville, 

con sin. 



FOR SALE: 2 meter FM remote base 
with 450 control, includes tranmit 
and receive on 34, 76, 94, with KW 
and 450 repeat, with auto patch and 
yagi beam for 2 meters and various 
other remote and repeater goodies. 
Contact Keith W7DXX (503) 
747-1 685- 
2-METER FM INOUE IC-20, Brand 
New, I & 10 watts, solid state, 12 
channel, w/Xtals, w /accessories, 
$235,00, Bob Brunkow 
206-747-8421, 15112 S.E. 44th 
Bellevue, Washington 98006. 

21ST ANNUAL DAYTON Hamven- 

tion will be held on April 22,1 972. at 
Wamplers Dayton Hara Arena. Techni- 
cal sessions, Exhibits, Hidden Trans- 
mitter hunt, Flea market and special 
program for the XYL. For informa- 
tion write Dayton Hamvention, Dept; 
S. Box 44, Dayton, Ohio 45401 . 

SI RPL1 S BONANZA 
NAVY VHF TRANSCEIVER. MAY-1 
200400 MHz. Complete with coil 
sets, discone antenna, manual, foot 

locker. $65.00 

ARMY TELETYPEWRITER 

SWITCHBOARD. BD-1G0, new, 10 

channels with regen relays, patching 

fields, cords, test meter, manual. Also, 

spares in chest. $30.00 

Other items, send stamp. F. L, Hajdu. 

41 Ledge Lane, Stamford. Conn 

06905. 



14 




& 



C 



^ ■ > ■ 






RM4L COfM * u t *«* ^ 
TIANiMinElt HADtf T27a/il 



Sam XeWy W6JTT 
12811 Owen Street 
Garden Grove CA 92641 



m t*'*-ij 



MoraftoiA inc 




Converting The 

T-278 TRANSMITTER 

For Two Meters 



he T-278/U transmitter is a two channel 
crystal controlled FM transmitter, As 
issued, it covers I 52—174 MHz with a power 
output of 25W. It is most commonly en- 
countered as part of the AN/VRC-19 mobile 
transmitter-receiver, but is used in a wide 
variety of other configurations. The trans- 
mitter requires a separate power supply and 
controls. Normally a DY 93-G power supply 
is used, but there is an ac supply, PP-804/U, 
which is used for base station configurations. 

Conversion consists of building a power 
supply, control circuits and a slight modifi- 
cation to the final amplifier tuning capaci- 
tor. Figure 1 is a schematic diagram of the 



power supply and control unit, The connec- 
tions between the power supply and control 
unit and the transmitter are simplified if you 
remove the existing connector and use a 
terminal strip for the power leads. A small 
butch plate can then be installed to mount 
two BNO connectors for the antenna and 
receiver antenna connections. 

After you complete and check out the 
power supply and before you connect it to 
the transmitter set the filament control so 
that the wiper is on the maximum resistance 
side. Then connect the power supply to the 
transmitter. Turn it on and adjust the 
filament control for 1 .25 volts as measured 
at the test point. 



MARCH 1972 



15 



3 A 



ti 



IIS VAC 




1500 PIV 
I AMP I K 



1200 
I W 




^/W 



1500 PiV 
(AMP 



6HY 



20 UF 
450 VDC 



/77 



1500 PIV 
I AMP 



Tl- 400 " 0-400 , 200 MA 
6,3 V , 5 AMP 
5.0 V t 2 AMP 



200 UF 
50 VDC ^ 



NOTC 



NUMBERS IN PARENTHESIS REFER 
TO PINS ON CONNECTOR 
P 401 / 501 




50 K 
2 W 



o 





80 UF 

450 VOC 



CARBON 
MICROPHONE 



I 



BIAS TEST 



6 3* 

5W 
^wv — 



3.3 K 
5W 



CH-I 



15 OHM 

50 PIV 
5 AMP 





9 cH*a 



O 



FIL-TEST 



4500 UF 
40 VOC 




777 



K" 12V, 3 POT RELAY 



Fig. I, Power supply and control T-278/U transmitter. 



O- 25 VOC <61 



O+380VDC(4) 



-0+275 VOC (5> 



-o+225V0Ct9> 



-O t£6J 



■O 1271 



-O (II) 



-O 02) 



-O+l 25 VDC (28) 



-O 6.3 VAC (71 



-O 63VAC (I) 



-O (29) 



-O «7I 
(13) 



The crystal frequency is calculated by 
dividing the desired operating frequency by 
32. Crystals should be ordered as CR-27/U 
type for use in an oven. Install the crystals in 
the oven and set capacitors 0-403 and 0-404 
to their midpoints. For two frequency 
operation it will be necessary to install a 
second 1AD4 in the socket labeled V^402. 
The second frequency cannot differ by more 
than ±1 MHz from the main frequency. 

Allow the set to warm up for at least 15 
minutes before proceeding with the follow- 
ing alignment. This time is required for the 
crystal oven to stabilize. Check to insure 
that the crystal oven is rated at 6V, 




1. Modification of the final tank circuit. 
This modification is not necessary if you are 
going to operate above 147,5 MHz, For 
coverage of the entire band it is necessary to 
solder two 1 in, diameter thin copper disks 
to the existing disk capacitor. Satisfactory 



disks can be made from a scrap of copper or 
brass sheeting, or the disks found in between 
88 mH loading coils can be used. 

Check the operation of the sliding short- 
ing bar. It can become erratic due to 
corrosion. In any event the fine pitch tuning 
screw is difficult to tune. The shorting bar is 
easily removed. Tuning is then entirely 
accomplished using the disk capacitor. 

2. Place the test switch in the test 
position and the tune-operate switch in the 
tune position. 

3. Connect the common lead of a VTVM 
to the chassis and plug the probe into jack 
J-40L Adjust Z*401 for maximum negative 
voltage. Detune to 90% of maximum. Move 
probe successively to J-4G2 f 403 and 404 
adjusting Z-402, 403 and 404 successively 
for maximum negative voltage. Nominal 
voltage at J-404 will be about 70V, 

4. With the probe in J-405 (driver grid), 
adjust Z-405 and 0-424 (driver grid tuning 
capacitor). There is an interaction between 



16 



73 MAGAZINE 



these controls so repeat the procedure 
several times. Nominal voltage at J^05 is 
—55 V. If a peak cannot be reached it may be 
necessary to solder a 5 pF padding capacitor 
across C-429, 

5. With the probe in the final grid jack 
(J-406) adjust the final grid tuning capaci- 
tors and the driver plate capacitor for a 
maximum negative voltage, 

6. Connect the VTVM across the plate 
current jacks. Watch out J The jacks are at 
plate potential. The meter reads 100 mA for 
each volt. 

7. Connect the antenna. Adjust capacitor 
C-448 for minimum current. Adjust the 
loading capacitor and the antenna coupling 
for maximum current while retuning G448 
for a dip, Place the tune— operate switch in 
the operate position and readjust capacitor 
C-448 for a dip. Adjust the coupling link to 
limit the plate current to 150 mA (L5V dc), 

8. Disconnect the VTVM from the plate 
current jacks and reconnect it across the 
balance jacks. If the final tubes are balanced 
the reading wili be zero. If they aren't 
balanced it will be necessary to adjust the 
final grid tuning capacitors to establish 
balance, 

9. Place the test switch in the off position 
and the tune operate switch in the operate 
position. The set is now ready for use. 

If no modulation is noted, check for a 2 V 
dc voltage on the microphone jack. If no 
voltage is present, you have an early set that 
hasn't been modified. To modify unsolder 
pin one of the microphone input transform- 
er T-401 from ground, and reconnect it to 
the wire going to pin 15 of the connector. 
This will provide dc for the carbon micro- 
phone. 

In practice, the transmitter has been used 
for both voice and AFSK RATX The 60012 
audio input (pin 14) is used for teletype. 

Precise frequency adjustment is provided 
by adjusting capacitors C-403 (frequency 1 ) 
and C-404 (frequency 2). The best bet is to 
have the net control station talk you on 
frequency as you adjust these controls, 

I was worried about the reliability of the 
1.25V filament tubes. This turned out to be 
groundless as the set has been in use for over 
a year without" a single tube failure. 

W6JTT 



i 



i 



i 



i 



NOW ACCEPTED FOR 

1 DAY C.O.D. SHIPMENT 



ON ALL OUR 



PRE-AMPS 



AND SOME OF OUR 



CONVERTERS 



If you need a low noise pre- amp in a hurry for communications or 
instrumentation, we can fill your order custom tuned lo any frequency 
from 5 MHz, to 475 MHl wrthm 24 hours by air mail or special deliv- 
ery. All you pay is our regular low price plus C.O.D. shipping 
charges, This rush service is also available on some of our stock 
converters. See Oct., Nov. and Dec, 1371 issues of 73 Magazine for 
out 2 page condensed catalog. Call us between 9AM and 4PM, Monday 
thru Friday except holidays <no collect calls pleases. If line is Dusy 
keep trying. 

PHONE: 212-468-2720 



J 



196-23 JAMAICA AVE 
MOLLIS, N.Y. 11423 



* 



LOW COST 
DIGITAL CLOCKS 
ft TIMER KITS 






Easy reading, 7 segment display tubes. Solid 
State MSI IC electronic components. Accurate 60 
cycle line time reference. Simple, push button 
settings. Clock displays hours, minutes and 
seconds. 10 minute timer, with seconds available. 

M «^ b ^«^ arantee Clock kit; $74.50 

ORDER TODAY Timar u - + t „ c n 

OR WRITE use your Mmer KIT: * M * DU 

FAR RFTAIK MASTER CHARGE Add choice of cases: 

L-M^ or BANKAMERICARD Metal clock case 

y^ , $10, Walnut $20. 

M ^ ^_- n ^J Metal timer case $8. 

■ ^^^p J Ca| i*- residents add 

\^^/L_I]MTERPHISES 5% ta * 

506 Main St. • El Segundo, CA 90245/772-6176 



MARCH T972 



17 



Set No. 1 



MANUFACTURERS BROADSIDES Circa 1870 



Cast-Iron Toys 
and Banks 




Statuettes 



Silver 



Tinware 
House Furnishings 



Granite 
Ironware 



Set No. 2 



Wood-working 
Machinery 



Bolts, 
Set Screws 



inW^" 1 



Fire Engines & 
t ,„«i* Railway Supplies 




Plows, 

Cultivators 



Axe & Hatchet 
Blades Adzes 



■ 



Set No. 3 

Firearms, Farm and 
Sewing Machines 



Metallic 
Cartridges 



Shotguns 
and Rifles 




FREE! poster of ELECTRICAL INSTRUMENTS 

With purchase of any one set of 5 broadsides @ 
S4.95/set ppd. We've seen these at 73 and they are 
beautiful. Authentic reprints of manufacturers' broad- 
sides 17 x 22 inches, black on a nice beige text paper 
with red border. Maine residents add 5% sales tax. 
Send to: Wentworth Press, P.O. Box 1 471, Portland, 
Maine 04104. 



Firearms 




Allen W. Porterfield, Jr. W2ISL 
41 Winnebago Road 
YonkersNY 10710 






Easier Conversion of 

Surplus Transmitter AN/ART- 13 



1 20V ac Power Supply 

Earlier conversions of the ART-] 3 
I transmitter used the 24 V dc relays 

from the separate dynamotor. In Fig. 1, I 
used no power supply relays because, like 
most buyers of this rig, I received no 
dynamotor. Two ac power supplies are 



controlled by primary 120 V SPST 
switches. 

The VFO supply is fixed with a voltage 
between 400 and 450V filtered dc. The 
813 power supply is 0-3500V. A 20O I W 
resistor added to the negative lead of the 




Front view of rig shows tuning knob of C3 t dynamic mike, speaker for side tone, and tuning chart 
MARCH 1972 19 



+MV 



LEFT END ART- 13 PEDESTAL 1 


IO 9 6 


5 4 2 1 J 


10 9 6 


5 4 2 1 P 

J 


ff f 


25V 

AC 

XFMR 

't — 'H 


Al 
24V 

oc 






♦ 


+ 


HV 
-_ 


450 

- VDC 


J L J L 


|J K (J k 


^>"€y 


IqI IqJ 



120 VAC LINE 



Fig, I. Power supply arrangement. Parts are: 25V 
transformer: WOW Lionel Corp. (or 2 12.6V, 
4A); 24V dc: Two 10A 12V dc battery chargers; 
4S0V dc PS: 225 mA minimum, 300 nriA max. 
(see text); HV PS: 1200V to 3000V, 200 mA (4 
866 rectifiers); Resistor: 20£l (20 jQ) I to 10W 
(on left end). 



OOUBLER 

EXISTING 

BI3 



-a/u 

TO 50jw 
LOAD 



FINAL AMPLIFIER 
8i3 {NEW) 




TO MOO KFMR 
TERM NO. T 



TO 10 VAC 
FIL XFMR 
Tl 



+ 450V 



Fig. 2. Ten meter diagram. Parts include: Medium 
base porcelain 25W lamp holder; L2 — 4 turns 
No. 18 on 1% in. form-tap thtd turn; L3 - 3i£ 
turns No. 14 on VA in. Hammarlund ribbed 4 pin 
plug-in form; Tl — transformer 10V t 4A t Zenith 
7.5 V and 2.5V series to add. 



larger supply gives instrumentation like the 
original. The existing panel meter reads 
0-200 m A of 81 3 plate current in the CW 
position of the emission switch. Plate volts 
may go to 3000 on CW. in the VOICE 
position, plate volts should not exceed 
1250 because the plates of the 811 As go 
pink and the percentage of modulation is 
lowered. The OFF position of the emission 
switch is not used. Neither is the cover 
interlock used (only 7 of the 10 pins in the 
U-7/U connector are used). Two 12V 
automotive battery chargers at 2 amps 
continuous duty operate the auto tune 
motor, etc., without filter or hum. 

10 and IS Meter Output 

There are no soldering changes nor 
drilling of the basic Collins rig. The 813 
tube becomes a doubler. Figure 2 shows 
the change of the plate circuit by changing 
the plate cap. Existing antenna terminal, 
RF ammeter and C, D, and E front panel 
controls are not used on 10, or 15 meters* 
The 813 doubler operates from the 450V 
power supply drawing 80 mA at resonance 
raising the 450V power supply current 
requirement to 300 mA. In the space left 



by removal of the LOW FREQ Oscillator, 
the 10 meter final is installed using a 
second 813. The plate current in this tube 
is read by the existing meter. Doubler 
resonance is found when the final plate 
current is peaked, A grid drive of 3 mA 
(external meter for initial tuneup) is suffi- 
cient to produce normal plate current on 
the 813 final. The PA GRID meter switch 
setting continues to read the input to the 
813 doubler. 

The aluminum bottom of the rig must 
be removed to peak the 1625 multipliers 




Bottom view shows plywood block used in place 
of metal bracket 



20 



73 MAGAZINE 



for 10.5 MHz and 14.2 MHz putting the 
pointer into the acceptable center scale 
range — 8.5 mA of grid current. A single 
turn loop around the 29 MHz coil couples 
the RG-8/U coax to a 1 kW amplifier at 
W2ISL. 

The RECEIVER terminal should be 
connected to the receiver antenna terminal 
with coax {shield goes to ground connec- 
tions). The microphone used has a switch 
to control the entire transmitter without 
hash in the receiver when not transmitting. 
A dynamic microphone is used from a 
surplus MARK II 19 set (new 3 conductor 
shielded cable) with a PJ068 plug. Ventila- 
tion holes in the sides of the rig suit 
RG-8/U coax. The final tuning capacitor is 
mounted on Va in. plywood (as insulation) 
in the vicinity of the coil L3, The grid 
tuning capacitor also used plywood as 
insulation with an insulated flexible cou- 
pling to a 2 in, long % in. shaft that passes 
through a new hole in the MX-128 panel 
(described in Surplus Schematics by Cowan 
Publishing Co.). 



1_ 

I SK.|[g g|V 



EXISTING 
CALIBRATOR 



Rl BATT 



/ 1625 x f 



C2 



i 



V_^ 



© 



EXISTING 

SPEECH 

AMPLIFIER 




10V-4A 
XFMR 
120V PRI 



] 



EXISTING 
DOUBLE R 



R2 



MOO 

XFMR 



© 



1/4 .n 
PLYWOOD 




FINAL 






C3 



* 



C6 



L3 



B^ 



l &JJJJJ/SJJjyjl F Mtl J JSSJ'J'JJ L 



1 




TERMINALS 




Close up top view shows coil location, LI is 6% 
(No. 14} turns on a 29/32 in. wood dowel All 
three coils have generously spaced turns. 



Link coupling from the doubler plate to 
final grid coil was used so that the doubler 
could be tuned to resonance at 29 MHz 
before and after the final was installed, An 
attempt to plate and screen modulate the 
813 doubler was unsatisfactory. Shorting 
2/3 of the turns of the final coil permits 
doubling in the second 813 for CW output 
on 6 meters. Circuit constants in the 
Figures are for 29 MHz because an AM 
carrier is feasible on 10 meters but not 15. 
Since the screen of the doubler 813 is not 
modulated, the G2 connection on terminal 
6 of the 81 1 A output transformer must be 
moved to terminal 7. A new insulated lead 
is run from terminal 6 to the screen (G2) at 
lug 3 of the new final 813 socket. Transfor- 
mer terminals are theaded with nuts. 

To save the $5 cost of USAF-NAVY 
Operating Instructions a table lists A and B 



MX- 
128 
PNL 


control settings for band edges and 50 kHz 




higher. 




1 




FREQ. (kHz) 


A 


B 




3500 


3 


1333.7 




3550 


3 


1455.7 




3900 


4 


673-4 calibrator check point 




4000 


5 


100.1 




7000 


7 


1333.7 




7050 


7 


1 394.6 




7200 


7 


1578.9 calibrator check point 




10,500 


9 


1 333. 7 1 5 mtrs 




10,525 


9 


1354.1 15 mtrs (advanced class) 




12,500 


11 


407.5 WWV check and 6 mtrs 




14,000 


11 


1333.7 




14,050 


11 


1364.2 




14,400 


11 


1578.9 calibrator check point 



Fig. 3. 10 meter output modification 



MARCH 1972 



21 






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RHR-2 



Note: We authofiof this article is T. L. Gr&enman WA 1KFZ 
who c/n be hearq daily working CW through the 04/9 1 
repeater on Mt Greyfock, Ma, 



Regency HR-2 transceivers are grekt 
little rigs for the money: however, lite 
all other ham rigs, there is always room for 
improvement. 

If you are a proud Regency owner and 
live where split channel repeaters exist, you 
know co-channel selectivity can be a prob- 
lem. The HR-2, 2 A (03-04 serial prefixes) 
use a single ceramic filter in the 455 kHz i-f 
strip for al! the selectivity. The easiest way 
to improve the selectivity then is to change 
this filter for a more selective unit. The 
sharper filter which cures the problem with- 
out causing other problems is a Murata 
Model CFR 455D which may be obtained 
from Murata Corp, of America, 2 Westches- 
ter Plaza, Elmsford, New York 1 0523. Prices 
are $14.30 each or SI 1 .30 for 3 or more. 

The new filter pin locations are shown in 
Fig. I. The new filter is longer and narrower 
than the original filter and its installation 
requires the drilling of 4 new holes in the P,C, 
board for its installation. In case Murata 
changes the case tab location with respect to 
the ground leads, check the two ground pins 
with an ohmmeter for continuity. 



,w o 


Ell 


ff A 


r f\ 


OUT ° 


r I L. i c n 


\J 


o 


i 


► 


— o 



IN/ 
OUT 







CASE 

TAB 




GNO 


O 




O 


IN/OUT 


O 




o 



GNO 



IN/OUT 



Fig. 1. Schematic diagram. 



To install the new filter: 

1 . Remove the old filter using a small 
(37W) soldering iron, taking care not 



to heat the board or pin excessively. 
The easiest method is to remove the 
solder from each pin, and then push 
the filter out. 

2. Next, using the new filter pins as a 
locator and Fig. 2 as a guide, drill four 
new holes (3 for leads and 1 for case 
tab). Index the new filter on the lower 
left pin hole as in Fig. 2. 

3. Place the filter into the holes and 
carefully solder the five places. 

4. Inspect the board carefully for solder 
shorts, etc. 

5. Put the unit back into its case and turn 
on the receiver. 

6. Find a channel with a weak signal on it 
and, using a diddle stick, adjust the 
quad coil (the i-f looking can next to 
the relay contacts) for clearest audio. 



ONLY HOLE USED FOR 
BOTH FILTERS 




@ NEW HOLES 

O EXISTING HOLES 

Fig. 2, Bottom view of receive hoard. Front panel 
on righ t 

Your selective receiver is now ready to 
go. You may notice a slight change in the 
squelch control action, and a slight improve- 
ment in receiver sensitivity. 



MARCH 1972 



23 




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See CORKY, W1KXM or WARD,W1WRQ 

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amplifiers, etc, 

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For mobile, fixed and portable operation by 
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12 - Bare Copperweld — 14 and 12 enamel 
copper — insulators — Baluns - Lowfosscoax — 
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and accessories — B & W - Coax switches - 
Dowkey refays - 72 ohm KW twin lead. 

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F,o«b* Hartford 

Please Include Postage 

CONNECTICUT'S OLDEST HAM STORE 







1 2 Channels 
with the 
Regency H R 

Gleaned from The Squelch Tate publication 
of the Northern Berkshire Amateur Radio 
Club (WA 1KFZ repeater), and submitted by 
WA J KM. 



Six channels may be adequate in most 
parts of the country, but on those areas 
where repeaters are springing up every few 
weeks, a few extra crystal channels could 
help. 

Fortunately the Regency HR-2 comes 
with a twelve position channel switch, so all 
you have to do to expand its coverage is add 
six more sets of crystals for the transmitter 
and receiver. There is room in the HR-2 for 
these, particularly if you are using an exter- 
nal speaker. 



36 P F CERAMIC 



KTAL 



SWITCH 

o— 




2-20 pf TRIMMER 



The process is simple. The six channels 
built into the HR-2 run down to the crystal 
sockets as you can see on page 1 2 of the 
instruction manual. All you have to do is 
add six more crystal sockets on a piece of 
Vector board 2% x 1 with .062" holes on 
.2" centers, plus six trimmers and six 36 pF 
capacitors per Fig, L Run short wires from 
the crystals to the switch and ground the 
other end of the circuit someplace handy. 
You can work out the mechanical problems 
or just tape things together, as you wish. 



24 



73 MAGAZINE 



MORSE CENTENNIAL 



Next April 2 will mark the 100th 
anniversary of the death of Samuel F. 
B. Morse. It is hard today to realize how 
great a debt the world owes to this painter- 
inventor and the magnitude of his contribu- 
tion not only to American life but to 
communications all over the civilized world. 
His experiments proved that using a prede- 
termined code, human intelligence could be 
transmitted long distances over a wire, with 
the speed of light- 
He was born in Cambridge, Mass,, 1791, 
and died 81 years later in 1872 in New York 
City. As a student at Yale (with a flair for 
sketching) he attended lectures on the new 
marvel, electricity. He and his brother 
Sidney invented a pump which was used on 
fire engines. 

But he needed a means of livelihood and 
for 22 years he painted portraits in the 
United States and Europe, where most 
American artists studied in those days. 

In 1832 he learned that a magnet was 
created if an insulated wire was wound 
around an iron core, and an electric current 
was sent through the wire from a Leyden jar. 
He felt that this property could be used to 
transmit human intelligence. He made num- 
erous sketches of such a system, and this led 
to his devising a crude sending apparatus and 
a code with which to identify the message. 
From 1832 to 1837 he worked on his 
invention at New York University where he 
was a teacher of the art of design and eked 
out a poor existence by painting portraits, 
too. 

In 1843 Congress voted $30,000 for the 
construction of his experimental telegraph 



line between Washington and Baltimore, and 
on May 24, 1844, Morse sent over the line, 
in the presence of many high officials, the 
famous message "What Hath God Wrought!" 

There were other efforts to devise practi- 
cal telegraphs all over Europe, but all of 
them were visual systems, leaving no record 
of the messages, Morse's machine, on the 
other hand, left a record on tape and was the 
first practical recording telegraph. 

Within a few years the whole Eastern 
United States was covered by short telegraph 
lines, Finally, in Rochester, N 4 Y M a move- 
ment began in mid-century to merge a 
number of them and within a dozen years 
more than fifty of the various lines had been 
combined into the Western Union Telegraph 
Co., which eventually covered the whole 
country. By 1862 a wire reached California, 
just seven years before the first transconti- 
nental train got there. 

Museums, colleges, railroad organizations, 
art galleries, professional and amateur tel- 
egraph associations, radio, television and 
historical bodies all will mark the centen- 
ary of the death of Samuel Finley Breese 
Morse, the man who annihilated space, on 
April 2, 1972. He died in New York City 
and is buried in the beautiful, park-like 
Green-Wood Cemetery, Brooklyn, N.Y., un- 
der a 1 5-foot-tall monument, surrounded by 
(he graves of 34 of his kin. 

Amateurs interested in more information 
on the Morse Telegraph Club should write to 
Joseph B. Milgrani President of the New 
York Chapter, 952 East 19th Street, Brook- 
fyn NY 11230, to whom we are indebted for 
this item. 



MARCH 1972 



25 



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modes. Controls for AF and RF gain, antenna 
trimming, BFO pitch. Plus: Product detector for 
superior SSB, S-meter, mechanical filter, head- 
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Robert L. Crenell, ex W8RHR 
5926 Beech Street 
Cincinnati, Ohio 45227 



UPDATING AN OLD RECEIVER 



You who fear to insert the tip of your 
soldering gun beneath the lid of your factory- 
made equipment, read no further. This art- 
icle will blow your minds, for the project it 
describes involves removing the crystal filter, 
diode detector, noise limiter, and part of the 
avc circuitry from an "outdated" diode de- 
tector AM/CW receiver. The parts and cir- 
cuits removed are then replaced with circuits 
and systems designed for the best reception 
of SSB, including just about the smoothest 
audio-derived age system to be found any- 
where. My conversion project was a 75A2, 



but the principles and circuits can be used in 
converting any receiver, 

I am presently in the throes of relearning 
the code* I unwittingly let my W8RHR li- 
cense lapse through simple inertia, and now 
must pay the price, (Why don't they make 
CW men pass an elocution test?) When I'm 
not copying practice code, I spend my time 
building and rebuilding, hoping to be ready 
next spring with a rig which will do justice to 
the excellent conditions which will prevail on 
the DX bands when I make my re-entry into 
the world of amateur radio. Naturally, 1*11 be 



MIXER 

PUATE 




X 

X 




F45SFB2I 



X 



?€ 



X455KQ200 



a 



-x 



?* 



"Ok 




i sr if 

GRfD 



i 



j 



-e 



^r 



Fig. I. Installation of 
Collins mechanical and 
crystal lattice filters. 
Fixed p adders are 82 
pF silver micas, and 
variables are 50 pF air 
trimmers. 



AGC 



MARCH 1972 



27 



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Height 


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Single Feed Line 


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1001 W. 18th Street • Erie, Pennsylvania 16502 



SSB. The first project on the agenda, there- 
fore, was the conversion of the 75A2 I pur- 
chased from a local ham. Of course, a mech- 
anical filter. And a crystal lattice for CW. 
And a good product detector and age system . 
with suitable noise limiting, This article is 
devoted to all of those who have failed to a- 
chieve the desired results when tackling a 
similar conversion. 

Most such failures lie in the area of the 
product detector and age. The installation of 
the filters is no problem; just follow the 
Collins directions. A Collins F455FB21 and 
X455KQ200 were mounted with their indi- 
vidual peaking components and the selectivi- 
ty switch in a minibox. This assembly 
replaced the crystal filter and its output coil, 
which were removed. The mixer output coil 
was also removed, and B+ to the mixer plate 
was fed in parallel to the filter input coils 
through a 10 mH rf choke (Fig, 1). 

The product detector and age system did 
not prove as simple. There were a number of 
criteria which I had to consider in designing 
this circuitry for the 75A2. It was essential 
to have a high degree of overload tolerance, 
a very efficient product detector, and lots of 
audio to rectify for the age. These charact- 
eristics, always desirable, are an absolute 
necessity in the 75A2. In this receiver, rf 
gain control is accomplished by varying the 
grid bias of the rf and // stages, as opposed to 
the more usual cathode bias control. The 
variable bias is tapped into the avc line 
through a resistive network which shunts the 
line and loads it rather heavily. In order to 
derive maximum benefit from the age system, 
it is desirable to run the rf gain control as 
nearly wide open as possible at all times. 
Thus, plenty of age voltage is required to 
prevent detector overload, and a high degree 
I of overload tolerance is required of the detec- 
tor. 

Other criteria were my desire to stay with 
tubes rather than go solid state in this parti- 
cular application, since I have had some un- 
fortunate experiences with transistor circuit- 
ry "taking off" in the proximity of heat-pro- 
ducing tubes. In addition, good product de- 
tector action is more difficult to obtain with 
transistors than with tubes, though some of 
the new FET circuitry seems to hold the an- 
swer. Simplicity (less to go wrong), minimum 
number of tubes (less drain on the 75A2 
power supply), and stable operation comple- 
ted the list of requirements. 

A number of product detector circuits 
were built, tried, and rejected. The double 



28 



73 MAGAZINE 



LAST IJF. XFMR 



IN67 (2) 




.01 



«— 



AU»0 
OUTPUT 



QOI 



Fig. 2, A product detector having excellent charact- 
eristics can be simply installed in most receivers 
using two lN67 r s in the above circuit. For use in 
the 75A2, however, this circuit did not provide suf- 
ficient output for adequate AGC action, even when 
amplified. 



diode type (Fig. 2) using 1 N67*s back to back 
has excellent characteristics, but the output 
is too low to yield the kind of age action 
required, even when amplified. Without ex- 
ception, the triode circuits I tried fed through 
considerable 455 kHz bfo voltage, even when 
the output was filtered using tuned traps. 
Too much stray coupling between audio and 
if stages. The result was erratic age action 
and bfo mixing in the //strip. Not good. In 
addition, triode and pentode circuits using 
cathode bfo injection were quite susceptible 
to overload. The low impedance presented 
by the cathode reduced bfo voltage enough 
to allow the if signal to over-ride the re-injec- 
ted carrier. 

Finally, the familiar 6BE6 circuit was cho- 
sen (Fig. 3). It out-performed the other cir- 
cuits tried in practically every parameter. 
Output was at least as high as with any other 
circuit... higher than most. It offered by far 
the best overload characteristics, and remain- 



ed linear and undistorted through an extrem- 
ely wide dynamic range, resulting in natural- 
sounding, undistorted audio. It was duly in- 
corporated into the 75A2. The .0039 juF 
ceramic by-passing the plate to ground redu- 
ces response above 3000 Hz and kills any 
455 kHz energy at the output. The circuit 
is stable and uncritical. The only precaution 
which should be observed is to keep bfo ener- 
gy out of the if strip. This point could be 
taken for granted, yet I know that many 
home-brew product detectors have failed to 
live up to expectations because the advanta- 
ges of the circuit were cancelled by bfo mix- 
ing in the ifs. Incidentally, don't neglect 
to realign the detector if transformer. Re- 
placing the heavy load of the diode detector 
with the light load of the product detector 
makes quite a difference in the secondary 
tuning and Q. 

With the product detector percolating 
nicely, I turned my efforts to the develop- 
ment of an equally satisfactory age system. 
In my experiments with other product detec- 
tors, I had derived age voltage by rectifying 
the output of either the detector itself, or 
its amplified signal, applying the resultant dc 
to the existing avc line through a 100K resis- 
tor. I tried both of these approaches with the 
6BE6 and was not able to obtain sufficient 
voltage by rectifying its output direct, in 
spite of its high level. When I amplified the 
output and rectified it, the resulting dc poten- 
tial was actually too high, but the voltage 
swing with modulation was still not great 
enough. Suddenly, the light dawned, and I 



TO HOT EfcDOF 
VOLUME CONTROL 



Fig. 3, Complete product 

detector and audio AGC 
system. Values of the capa- 
citors switched by the "Fast- 
Slow" switch will vary from 
receiver to receiver. Cut and 
try is almost the only way 
to determine the value of 
the "Slow" capacitor. The 
"Fast" capacitor will ordi- 
narily be the original capa- 
citor shunting the AGC line 
in most receivers. Break at 
X to include the noise li- 
miter circuit in Fig t 4. 




200-250 
VDC 



TO AGC SUM? 41* 
LINE 



MARCH 1972 



29 



Hi 



realized that I had been overlooking the ob- 
vious impedance mismatch between ghe out- 
put of a tube and the low impedance of the 
diode rectifier, The cathode follower of 
Fig. 3 was quickly constructed and connected 
to the hot end of the volume control, A 
transformer hook-up was tried experimental- 
ly, but the cathode follower proved far su- 
perior in providing the desirable wide swing 
of age voltage for a small variation in input 
to the detector. The unused 12AX7 triode 
was originally the avc amplifier in the Collins 
circuitry. I definitely recommend the cathode 
follower age derivation as vastly superior to 
other methods commonly in use. 

The iOOK resistor was retained to avoid 
excessive loading of the age rectifier. AGC 
action is so good that 1 only have to reduce 
the r/gain in the presence of strong local sig- 
nals. The final touch is the variable time con- 
stant. In the CW position, only the original 
.1 juF capacitor shunts the age line; switching 
to the SSB position adds a 4 juF miniature 
electrolytic, and increases the discharge time 
to about ,6 seconds. The attack is only sof- 
tened slightly ...just enough to prevent the 
overshoot "click" at the beginning of a trans- 
mission or after a pause. Other receivers will 
require much smaller values of capacitance if 
their age lines are less heavily loaded than 
that of the 75A2. 

So far so good, Now for the noise limiter. 
Not so good. Every conceivable type of noise 
limiter circuit was tried. At first, I consid- 
ered a noise blanker, but the cumbersome 
circuitry, space and power requirements dis- 
couraged this approach. I then turned to 
simpler possibilities. Using fast time constant 
age voltage to an early //stage did not prove 
as satisfactory for me as it apparently has for 
at least one commercial manufacturer. Most 
series and shunt clippers using diodes created 
audio distortion to a degree which I found 
objectionable when they were adjusted for 
satisfactory limiting. In addition, they did 
not provide the advantage of limiting ahead 
of selective circuits, which is so desirable* 
RF and if clipping proved only marginally 
effective. I searched the manuals and maga- 
zines, but never found a circuit which sur- 
passed the one shown in Fig, 4* It causes 
some audio distortion, but it is bearable, and 
limiting is sufficient under most conditions. 

The diodes are biased by contact poten- 
tial, and peaks exceeding it are shorted to 
ground through the appropriate diode. Sili- 
con and germanium diodes were tried, but 



FROM 6BE6 
PLATE 



£20 K 



TO VOLUME 




£20 



tf 



CONTROL AND 
CATHODE 

FOLLOWER 



]{ 



220 



Fig, 4. The noise limiter. Audio distortion be- 
comes objectionable on strong signals, so the 
limiter should be switched on only when needed. 
This circuit is at its best on weak signals, which 
can be copied even through heavy QRM. An i-f 
noise-blanker would be much better, but space 
and power considerations required a compromise. 
It's far from the ultimate, but it works better than 
most circuits and is at least as good as any other 
tried. 

seemed to cause more distortion than the 
6AL5 because of their greater sensitivity. This 
can be adjusted, but the 6AL5 was there, so 
I used it. The 220 pF capacitors suppress dc 
spikes, which are troublesome at high clip- 
pink levels and relieve some of the harmonic 
distortion generated by the clipping action. 
This clipper definitely cannot be left in the 
circuit at all times. It should be used only 
when needed, since strong signals will be clip- 
ped and distorted. It is especially useful when 
hunting through QRN and atmospheric rub- 
bish for weak signals. 

The addition of a 5:1 reduction drive and 
oversized tuning knob completed the first 
phase of my 75A2 conversion. It's almost 
overload proof. AM reception is possible, 
though definitely inferior to diode detection, 
The product detector— age system is at least 
the equal of anything in current commercial 
usage, and a great deal better than some. All 
in all, I don't feel I could be better off with a 
brand new receiver. And that's the beauty of 
home brewing. I get something for less than 
it would have cost off the shelf, learned a 
few things in the process, and got a real feel- 
ing of satisfaction out of making it work. 

What's next? A 6 meter conversion of 
the old 1 1 meter band, continued efforts to 
develop a satisfactory noise limiter, and a Q 
multiplier rejection filter built right into the 
75A2, of course! 

W8RHR 



30 



73 MAGAZINE 






Experience is the best teacher, ob- 
viously, so it is possible that much can 
be learned from the problems that 
arose during the February 197] Los 
Angeles earthquake. The Los Angeles 
SCM lias published an interesting and 
lengthy report on the effort, and I 
believe that the conclusions he 
reached will be of value to every club 
and individual concerned with pro- 
viding emergency amateur radio com- 
munications. 

Disaster Preparation 

Operators for a particular Emer- 
gency Operating Center should be 
recruited from a diverse physical 
area. The W6IN Society had many 
regular members unable to assist as 
they were personally involved in 
attempts to provide solely for their 
immediate families. There is a need 
for the individual radio amateur to 
be well prepared as well as the 
emergency oriented groups in 
which he participates. He must have 
his own family cared for in order 
that he can even be available in 
time of disaster. 

Radio amateurs should establish 
an emergency kit or list of required 
items to take on an emergency 
operation. This kit should contain 
sufficient items to provide food, 
clothes, spare parts, etc., which 
might be needed to render a man 
self-sustaining for 72 hours in the 
field, '* 

The telephone tree (one individ- 
ual calling a list of persons who in 
turn call an established list on the 
telephone) usually is excellent for 
exercises and drills, but it proved 
useless within this disaster area. 
There was no telephone service. An 
activation system involving persons 
reporting to a gathering frequency 



or a specific location is to be 
preferred* 

Emergency power and equip- 
ment must be tested regularly at 
definite intervals and for substantial 
periods to insure its being in suit- 
able operating condition. The 
Emergency Operating Center gener- 
ator that failed had been tested 
weekly on Mondays for fifteen min- 
utes, but had never been run for 
any substantial period of time, The 
fuel pump quit, it lacked sufficient 
radiator water (water mains were 
broken by the quake}, and the fuel 
supply was low. 

Should an Emergency Operating 
Center become unusable it is vital 
that some provision be made for a 
portable command post (preferably 
a mobile command post} with eith- 
er permanent equipment installed 
or provisions made for equipment. 
A mobile command post should not 
be stored at the same point as the 
Emergency Operating Center or 
both may be lost at the same time. 

Contacts established with local 
business firms, concerning the use 
of necessary equipment accessories 
and supplies in time of disaster or 
need, will prove extremely bene- 
ficial. 

It must be remembered that 
amateurs are supporting local gov- 
ernment disaster efforts as com- 
municators and are not responsible 
for much of the planning, securing 
of goods and administrative de- 
cisions. Also a single unpleasant 
confrontation with a city official 
can change the image presented by 
the entire operation. 

The role assumed in this effort 
unfortunately encompassed more 
than that of a communicator to the 
extent of becoming an administra- 



tor in a decision-making position. 

In retrospect this is undesirable and 
undermining to the general efforts 
of amateur radio to establish better 
working relations with public ad- 
ministrative agencies. 

It is also noted that it is highly 
desirable to have available to the 
proper administrative decision- 
makers the ability to monitor other 
services (hospital, police, fire, etc.) 
at the Emergency Operating Center. 

A professional appearance of the 
radio amateurs making contact with 
disaster officials is highly recom- 
mended. This would include proper 
dress and the presence of mature 
attitudes. 

Overall communications coor- 
dination efforts with other amateur 
radio groups hoping to provide 
some service in the disaster area is 
vital. Groups of well-intending ama- 
teurs—unless recognized by the 
coordinating disaster group offi- 
cials — can defeat the overall effort. 
Individual radio amateurs should be 
affiliated with a well-disciplined 
emergency group prior to a disaster 
if they expect to be fully produc- 
tive during a disaster. Amateur ra- 
dio groups operating in such a 
situation must have good communi- 
cations horizontally among those in 
charge during the disaster situation. 

A universally recognized insig- 
nia, picture ID card should be 
established for those with a purpose 
in a disaster area. Any such ID must 
also be made clear to proper au- 
thorities engaged in the disaster 
operations. 

During the Disaster 

To ''be prepared" is insufficient 
Established communications groups 
must volunteer their services to 



MARCH 1972 



31 



affected areas. Without such volun- 
teering W6IN, for example, would 
have been hard-pressed to provide 
adequate communications to the 
City of San Fernando on an emer- 
gency basis* 

Shifts for communications per- 
sonnel should be established as ra- 
pidly as feasible for continuity and 
efficiency. 

A quartermaster of radio gear, 
accessories and other equipment to 
be used during operations is neces- 
sary to coordinate their issuance. 
Some personal radio equipment was 
"lost" through inadequate control. 

Some panic information was dis- 
seminated to the public by the 
news media pointing up the neces^ 
sity for strict control over any 
media releases. Speculation and ru- 
mors should be discouraged on 
amateur radio bands as well. 

Comments and Conclusions on 
Health and Welfare Messages 

When mail took a significant 
time to cross the country and long 
distance calls cost considerable 
sums, amateurs performed a real 
service by relaying messages that 
were mailed for final delivery. The 
attitude of many amateurs regard- 
ing mailing of traffic today can be 
summed up by one comment : 
"When offering to send a message 
without a phone number to a per- 
son with either an unlisted number 
or a number fisted under another 
last name, the originating station 
would be well advised to provide 
the originating party with a free 
post card rather than essentia f/y 
offer one at the expense of stations 
in the delivery area. " 

Individuals make long, futile ef- 
forts to locate numbers. Some at- 
tempt to ditch the stuff on some- 
one else, possibly a mile or two 
closer, although the addressee 
would be a local call for the first 
station if a phone number were 
available. Also it is difficult to get a 
letter into the postal system at a 
point where delivery will be 
prompt, (A card put into the mail- 
box after the last pickup of the day 
stands little hope of next-day deliv- 
ery.) With the present air mail 
handling of first class mail, any 
radio message eventually mailed 
will probably reach its destination 
later than had it been mailed at the 
source. 

Many of the instant service nets 
have resorted to not taking traffic 
listings without telephone numbers 
and liaison with them is sometimes 
necessary for the older, basic traffic 
nets. Especially in a disaster, the 
delivery stations are sufficiently ov- 
erloaded with traffic to be justi- 
fiably annoyed at having to devote 



large efforts to researching tele- 
phone numbers. Inclusion of tele- 
phone numbers on messages cannot 
be overemphasized. 

Additionally it is suggested that 
the National Traffic System, the 
three Area Staffs and the ARRL's 
Communications Manager should 
establish special provisions for 
handling large volumes of traffic in 
disaster situations that can be acti- 
vated readily. There has been no 
indication of any special, organized 
efforts on a large scale within NTS 
to accommodate the large traffic 
volume occurring only days after a 
national exercise in emergency pre- 
paredness in the form of the 
ARRL's S imulated Emergency 
Test, "SET." Along the same lines 
more emphasis is needed on faster 
routing and delivery of traffic in 
NTS (traffic originating in NTS 
after the quake typically took three 
or four days to reach California 
NTS circuits). In addition to sim- 
plified routing techniques the use 
of simplified message forms (as 
used on the instant service nets) 
should be objectively investigated 
for use in disasters as well as in- 
creased use of modes other than 
CW. 

Inquiries into Disaster Areas 

Most reports on disaster opera- 
tions conclude with the thought 
that inquiries should not be sent 
into disaster areas. The previous 
paragraphs are evidence that these 
efforts have not exactly been heed- 
ed. In a disaster where 65 people 
died out of a population of over 7 
million, it could be seen that the 
answer to "Are you OK?" was 
"Yes." If there was any need for 
help, no doubt the affected parties 
would have requested help. How- 
ever, the enhancement of the radio 
amateur's image was felt by the 
participants to have justified the 
effort. 

Two types of inquiries some- 
what amazed a few amateurs. One 
was an inquiry addressed to a per 
son at an "unknown veterans' hos- 
pital in or near Los Angeles." In 
other words, the originators were so 
concerned about Uncle Charlie they 
were glad to take advantage of free 
services to inquire about his state, 
but not quite interested enough 
prior to the disaster to even know 
where he lived. 

The other was a public service 
group that originated all their 
health and welfare traffic with the 
organization's signature rather than 
the originating party. Delivering 
amateurs felt somewhat embarras- 
sed at receiving comments like 
"What is this all about?" when 
delivering "Are you OK? From the 



XYZ County, East Coast State 
Emergency Helpers Organization" 
message to a person living fifty 
miles from the quake center. 

Overall Conclusions 
and Comments 

It is noted that all disaster com- 
munications were handled by voice. 
With the exception of the Southern 
California Net on CW and the Navy 
MARS RTTY circuit, the health 
and welfare message load was han- 
dled by voice. CW, albeit more 
efficient for exchange of message 
traffic between experienced opera- 
tors is a skill that has not been 
developed by enough amateurs to 
result in an effective disaster ser- 
vice. Complaints were voiced by 
Southern California Net members 
about lack of coverage in many 
areas which resulted in many mes- 
sages being delayed even more. 

The ease of training operators, 
reorienting an operation (setting up 
separate frequencies for different 
areas, for instance) and making 
large numbers of people aware of 
what's happening and capable of 
helping, makes voice by far the 
more effective means of disaster 
communication. 

The Future 

While it was a learning situation 
for Los Angeles AREC, this disaster 
communications operation demon- 
strated the value and merit of 
AREC. Several steps are being ta- 
ken to improve and develop AREC 
in the Los Angeles Section under 
the leadership of the Section Emer* 
gency Coordinator, WA6QZY. FM 
has been clearly demonstrated to be 
a highly effective form of mobile 
and emergency communication for 
which reason 146.82 MHz FM sim- 
plex has been designated as the 
section-wide AREC emergency and 
mobile frequency in the Los An- 
geles Section. 

Through the cooperation of the 
Edgewood Amateur Radio Society, 
Inc., the W6FNO repeater will re- 
peat 146.82 MHz to 146.70 MHz. 
Also the Palisades Amateur Radio 
Club of Culver City has made their 
repeater, WB6ZDI, available to Cul- 
ver City AREC (146.61 MHz in, 
147.33 MHz out FM). Hopefully 
other radio clubs will also provide 
such support of AREC. 14302 kHz 
has been designated as the section's 
health and welfare frequency. A 
command channel on 2 meter FM 
for ECs, SEC, SCM and their assis- 
tants is being developed as is a high 
frequency band frequency for use 
as a gathering point. Discussion is 
also being given to an information 
station which would be used on a 
regular basis as an Official Bulletin 
Station. 



32 



73 MAGAZINE 



BUI Hoisington K1CLL 
Far Over Farm 
Peterborough, N.H. 



Solid State Tuneable IF 



Fixed-Tuned, 1.65 MHz IF Companion Unit 
to 28-30 MHz IF in January, 1970 issue of 73 



This is the detailed low-down on the 
construction of some practical i-f stages for 
amateurs, including windings, cup-cores, 
etc,, for 1.65 MHz, employing techniques 
you can use on other frequencies as well 

There are several 45 5 kHz i-f strips on the 
market which work quite well, however 
these are a compromise in the trade-off on 
low image versus selectivity- The easiest way 
for the home-brewer to be sure to obtain 
narrow-band selectivity at low cost and in 
battery-portable form is to use a low i-f 
frequency. This means image trouble unless 
more conversions are used. If this is done 
both freedom from image and selectivity 
result. And if you tap into the outputs of 
both i-f's you can have an instant choice of 
broad or narrow bandwidth on a switch. The 
business of crystal filters is left to the 
professionals, resulting in receivers in the 
hundreds of $. 



+■ o 



12 VOLTS 



**£• 



rn 




H> 



Fig. 1. Schematic of the fixed-tuned first stage, 



DC Collector Voltage at the Ground Level 

This is definitely good. Fig. 1 shows the 
simplicity of the first stage, which is fixed- 
tuned. What could be simpler? And it works 
very well. One coupling capacitor to the 
base, one bypass capacitor for the emitter, 
and that's it. All coils have one side 
grounded to the copper-clad baseboard. 

Base Resistors 

A number of tests were run on these 
items, which were found to be non-critical, 
as long as the ratio is held to furnish the 
needed base turn-on voltage. Values from 5K 
down to 250 ohms were tried for Rl (Fig. 
1), At 250 ohms the shunt resistance across 
the base began to lower the gain. Naturally 
R2 has to be changed for every change in 
Rl. A ratio of between four to one and six 
to one is good, I settled for 2.2K for Rl and 
12.5 for R2, but this ratio may change a 
little for other transistors. 

Input Tuning Not Required 

This also was tested carefully. The out- 
put of the mixer from which the 1.65 MHz 
i-f was derived is already tuned, so it is really 
a question of how many tuned circuits you 
want to use. Various arrangements of tuned 
base coils were tried, with little increase in 
gain noted, so tuned circuits were left out of 
the input. 



MARCH 1972 



33 



Interstage Coils 

A number of different types of i-f trans- 
formers were wound and tested, with dif- 
ferent iron cores, the matter of size entering 
here to a considerable extent because there 
will be a number of stages and also a 
hand-carried rig has to be kept as small as 
possible. 

You can get real fancy here in the matter 
of i-f transformers, and wind them up with 
Litz wire, original German "Litzendraht," 
which is made up of many strands of small 
size enamel wire, example, "5/40." This is 5 
strands of no. 40 enamel wire, and below 
about 7 MHz it does increase the Q to any 
remarkable extent. To match the benefits of 
this wire you can use fancy cup cores of 
powdered iron from Holland, and end up 
with a Q of 300 to 400 around 455 kHz. 
But, and it's a big but, you can't hold it! 

The necessary air gap changes, and 
temperature, moisture, etc., put in their two 
cents worth also. 

So, in one sense, it is better, at least more 
permanent and easier for the home-brewer 
to use more stages each with a lower Q and 
greater stability. For the narrow-band 
section we will work on this question a little. 
One more tuned circuit, with another stage 
allows all of them to run with conservatively 
longer life, practically no heating, no feed- 
back, and is much better if you want a little 
more selectivity. 

That problem has already been solved 
here by having the choice of two band- 
widths. 

Threaded Core IPs 

Refer to Fig. 2 for these items. When you 
random wind by hand, which is pretty easy 
and works all right, wind on 25 turns first, 
then one pi of 50 and then the other, as 



6-32 



F3GURE 2 
THREADED CORE 
IF DETAIL 



50 TURNS 



50 TURNS 



6-32 TAPPED 
PHENQUC FORM 




25 TURNS 



9AKELITE 

MOUNTING 
PLATE 



shown in Fig. 2. These separate pi windings 
increase the Q quite a bit, helping with 
random winding which does not have the 
best of Q ordinarily. 

Inserting the 6/32" iron core from the 
top keeps it in the main body of the winding 
for Q and coupling, and then reaching into 
the 25 turn part, serves to tune a little above 
and below the desired frequency for trim- 
ming, which is always needed* 

As mentioned, you can' make coils this 
way, or get real fancy. That's up to you. L2 
is wound in the low place between the two 
fifty turn windings. L2 is generally a small 
number of turns, say from 2 to 5 turns. See 
final schematic and coil table. 



What Not to Do 

With three tuned circuits on 1 .6 
one in the 28 to 30 mhz mixer collector 
output, and one in each of the two i-f stages 
being detailed, it seemed only natural to try 
and achieve more Q with bigger and better 
powdered iron cores. Having a large selection 
of these, from some real small ones like 
1/32" diameter O.D., up to the 1/2" loop- 
stick sections, which same can be cut with a 
file, I wound up some 1,6 MHz coils with 
various turn numbers from 50 to 100. Well, 

the Q went up, but so did the troubles! The 
most nasty kind of feedback you ever saw 

crept in and then settled down to stay! And 

I couldn't neutralize it. 

To cut it short, it was magnetic feedback, 
from the collector coil to the base winding 
on the previous collector coil, as I found out 
finally by removing the first stage and 
checking with just one transistor running, it 
oscillated all right, whenever the base coil 
was within several inches of the collector 
coil. Industrial designers (technicians) in 
large receiver companies can well laugh, 
someone else is paying for their days! Even 
though these windings were separated by 
more than three inches, trouble still 
occurred. 

At last I remembered building a 16 to 18 
kHz sideband filter some years ago (it 
worked good by the way) where 1 had to use 
tinned iron shield cans to keep down the 
magnetic coupling. It all came back to me 
then. 



34 



73 MAGAZINE 



FOR THE PROFESSIONAL AMATEUR 



SONAR (2 meters 




TRANSMITTER 

Dtrnutpc < fr ° m 144 *° 

l\kl/LlffLRw 148 MHz) 

COMPLETE FLEXIBILITY FOR 
FOR MOBILE -BASE -HAND HELD 






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$ 8 Ghannete with fnst&M #iis& fim tort 

;^v;i|Rjp^ '^4 i8y : ^otifpisf t Wter for': acliaoeni -oft^^rmt;;-;^ 

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K^wSSfflHS 




Model 2307 
VHF-FM 

TRANSCEIVER 

5 CHANNELS i.gwmin 

HAND HELD PORTABLE 

* Provides immediate voice con- 
tact with Base Stations, Mobile 
Units and other portable trans- 
ceivers * Compatible with ALL 
2-way communications systems 

• Snap-in Nicad Battery Pack 
cartridge * Receiver and trans- 
mitter can be operated on inde- 
pendent frequencies • Electronic 
mode switching/no relays * Re- 
ceiver and transmitter sections 
are Individual modules for easy 
servicing * Sensitive adjustable 
squelch 

complete with 
collapsible antenna 
and shoulder strap. 
Less crystafs & battery cartridge* 



Corporation 73 Wortman Avenue, Brooklyn, N.Y, 11207 



The Answer 

The solution for compact units is to 
enclose the outside of the winding with 
powdered iron as well as having a center 
core. This causes the magnetic field to curve 
back in a sense, into the coil again , instead 
of travelling through the "near field" over to 
the base coil winding, where you most 
decidedly do not want it. 

These kind of cores are known as cup 
cores, and there are millions available 
practically for free. Most of the i-f trans- 
formers made for tube i-f's have some 
beauties in them. Actually, two each. One is 
illustrated in Fig. 3K y with the winding I 
used, in Fig* 3B^ I just happen to have (did I 
mention my 45 foot junk box?) a lot of 
these because of some ten years of work 
with sub-miniature battery tubes, like the 
1V6, 1AD4, etc. So, you take the insides 
right out of one of these transformers, like a 
Miller no. IOC, and there are the two cup 
cores which are good for at least 455 khz up 
to several mhz. 



FIGURE 3A 
CUP CORE 




U 
25 

TURNS 

NO 25 

DSC 




FIGURE 3& 
WINDING FOR 

1.65 MHZ IF 



5TURN 

OUTPUT 

WINDING 



THI5 COIL SUPS OVER 
THE CENTER CORE AND 
INSIDE THE CUR 

Fig. 3. A. Cup core and B. winding 
for 1.65 mhz i-f. 

They do a swell job on L65 mhz, with 
plenty of gain, no neutralization needed (so 
far) and, using 500 pf or more tuning, the 
variations in collector capacity with current 
on avc action can be eliminated. 

The use of a large C also drops the 
impedance down for a better match with the 
transistor collectors. 

A completely enclosed cup core in one i-f 
stage with a cover over the top, shown open 
in Fig. 3 A, can be used very close to another 
stage without feedback, due to the greatly 
lessened external magnetic coupling. When 
you go in for real compact assemblies you 
will have to watch out for the electrical 
coupling (by capacity). Toroid coils are 



MARCH 1972 



35 



" S u METER 




IK 

1 K pot, 

100 ohms 

TOO ohms 

5.6K 

47 K 

10K 

Table 1. 



I 65 MHZ 
OUT TO 
NARROW -BAND 
LR STR!P 



Frg, 5, Final schematic. 



often used for this purpose but they run into 
money and are much harder to wind. 

A Special, Simplified AVC 

For some time now I have not been 
completely satisfied with the avc system 
found in most books for economical type 
circuits, which I have often used myself. 
This one is shown in Fig. 4, 




Fig, 4. "Old" avc circuit to be avoided 



R2 and R3 tend to load the diode with 
dc when you adjust them for best operation 
of the controlled stage, resulting in af 
distortion at certain levels of signal. As 
noted in Fig. 4., do not use the circuit shown 
there. Use the one shown in Fig. 5, the final 
and complete schematic, which has the new 
simplified circuit, It still does not use an 
additional transistor, but it does isolate the 
af from the avc action and produces beauti- 
ful af, by using two diodes, 

DI is a regular amplitude demodulator 
used solely for af. A secondary winding and 
D2 generate the dc voltage for the avc line. 

In the absence of a signal, point A sits at 
about one volt negative from the plus 12 



volt bus, resulting from the combination of 
D2, Rl, and R2 S and the negative bus which 
is also the ground plane in this i-f unit. This 
causes Ql to operate at normal gain with a 
few milliamps of current. 

An incoming i-f signal will build up a dc 
voltage through Dl making point A go 
through zero volts and, on a very strong 
signal up to around 2 volts positive with 
respect to the 12 volt bus. This of course 
automatically reduces the curent and gain of 
the avc controlled first i-f stage. 

Rl and R2 can now be juggled for the 
best avc action with no effect at all on the af 
demodulation. 

Completed Circuit 

As mentioned, Fig, 5 shows the final 
schematic which operated in an excellent 
fashion with the 28 to 30 MHz tuneable 
section. The use of this tuneable i-f section 
allows the assembly of hand-carried battery 
portable rigs using crystal control all the way 
from the transmitter through to the local 
oscillators. The bandwidth of this fixed i-f 
on 1.65 MHz is about 50 to 100 kHz, 
depending on signal strength, and makes an 
excellent unit for search, tune-up, and 
medium distance reception with various 
front ends, antennas, converters, etc., on 
432, 1296, and 2400 MHz, This amount of 
bandwidth allows your converter local oscil- 
lator crystal as well as the transmitter crystal 
of the lad on the other end of the QSO to 
"move" a little (they will!). 



36 



73 MAGAZINE 



William F, Turner WA0ABI 
5 Chestnut Court 
Saint Peters MO 63376 



CHECKING ZENER DIODES 



Over the past several years the cost of 
producing ultrapure silicon and the 
resultant devices has decreased at an ex- 
tremely rapid rate. This reduction has been 
reflected in the cost of all silicon semicon- 
ductors. Perhaps the area in which the 
change has been most noticeable is in 
bipolar transistors, but at the same time 
the same reductions have been made in 
zener diodes too. Almost monthly one 
magazine or another features an article on 
the subject of testing and grading the "10 
for 1 * or "100 for" type of transistor. The 
subject of putting surplus zener diodes to 
use has not been popular and perhaps for 
this reason the price of unmarked zeners is 
extremely low. One large mail order house 
currently lists an assortment of 20 for less 
than $2. What then is needed to test and 
categorize these diodes? Fortunately the 
procedure and the equipment are simple. 
First of all we must supply a voltage in 
excess of the zener point of the diode 
under test. This may be a special power 
supply built for the purpose or voltage may 
be taken from a bench supply or stolen 
from other equipment. We must also limit 
the current through the diode to a safe 
value in order not to exceed the dissipation 
rating of the device. 

The diagram shows the simple setup in 
use at this QTH. The fixed resistor serves a 




Fig. L 



current limiting function only. The volt- 
meter, which may be any VOM, VTVM, or 
panel meter, measures the drop across the 
zener. The potentiometer acts as a voltage 
divider and allows the voltage applied to 
the diode to be varied above and below the 
regulating point. If you are fortunate 
enough to have a bench supply available, 
the internal variable feature may be used 
and the potentiometer eliminated. 

The constants given were chosen with 
an eye to minimum dissipation within the 
diode. The maximum current is limited to 
1 mA, making this setup usable for a wide 
range of diodes types and sizes. Other 
constants may be selected if only higher 
power types are to be checked. 

In use, the unknown diode is connected 
across the terminals with the indicated 
polarity, (Use trial and error if the diode is 
completely unmarked.) Always start with 
the potentiometer at the low voltage posi- 
tion and slowly increase the applied voltage 
until there is little or no increase in meter 
reading with increase in voltage. This is a 
rather abrupt indication. You will have no 
trouble detecting it. This is the voltage at 
which the diode will regulate. As they are 
checked, mark each diode with the correct 
voltage. A scrap of masking tape is a simple 
way of doing this. 

A shorted diode will give no meter 
reading at any voltage — an open diode will 
allow the meter to read the supply voltage. 

There remains one fly in the ointment. 
You will have to learn by experience the 
dissipation ratings of the various physical 
sizes of diodes. A short look at the actual 
size pictures in parts catalogs will be a good 

start. 

. . .WA0ABI 



MARCH 1972 



37 



HIGH GAIN • LOW NOISE 



40 dB GAIN 2.5-3.0 N.F 
@ 150 MHz 




35 dB power gain, 2.5—3,0 dB 
N.F. at 150 MHz, 2 stage, R.F. 
protected, dual-gate MOSFETS. 
Manual gain control and provi- 
sion for AGC. 4-3/8" X 1-7/8" 
X 1-3/8" aluminum case with 
BNC receptacles and power 
switch. Available factory tuned 
to the frequency of your choice 
from 5 MHz to 350 MHz with 
approximately 3% bandwidth. 
Up to 10% B.W. available on 
special order. 
Model 201 price: 

5—200 MHz , . .$21.95. 

201—350 MHz. .$24.95 , 



MUC 3 to 5 dB MAX. N.F. 

20 dB MIN. POWER GAIN 



*•*##- 




The Model 202 uses 2 of T.I.'s 
super low noise J-FETS in our 
special circuit board design 
which gives a minimum of 20 
dB power gain at 450 MHz. 
Stability is such that you can 
have mismatched loads without 
it oscillating and you can retune 
(using the capped openings in 
the case) over a 15—20 MHz 
range simply by peaking for 
maximum signal. Available 
tuned to the frequency of your 
choice between 300—475 MHz. 
4-3/8" X 1-7/8" X 1-3/8" alu- 
minum case with BNC recep- 
tacles and power switch. 
Model 202 price: $31.95, 



VHF FM RECEIVER 
11 CHANNELS • 135-250 MHz 




• 11 crystal-controlled chan- 
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of frequencies from 135 — 250 
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1^4 MHz wide. • I. F. band- 
width (channel selectivity) avail- 
able in your choice of +/ — 7*5 
kHz or +/— 15 kHz. • 8-pole 
quartz filter and a 4-pole cera- 
mic filter gives more than 80 dB 
rejection at 2X channel band- 
width. • Frequency trimmers 
for each crystal* • .2 to .3 
/ivolt for 20 dB quiet- 
ing. • Dual-gate MOSFETS and 
integrated circuits. • Self-con- 
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speaker jack. • Mobile mount 
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Case, 6" X 7" X 1 3/8". 
Model FMR-250-11 price: 

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181—250 MHz $119.95 

Price includes one .001% crys- 
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2 RF stages with transient pro- 
tected dual-gate MOSFETS give 
this converter the high gain and 
low noise you need for receiving 
very weak signals. The mixer 
stage is also a dual-gate MOS- 
FET as it greatly reduces spur- 
ious mixing products — some by 
as much as 100 dB over that 
obtained with bipolar mixers. A 
bipolar oscillator using 3rd or 
5th overtone plug-in crystals is 
followed by a harmonic band- 
pass filter, and where necessary 
an additional amplifier is used 
to assure the correct amount of 
drive to the mixer* Available in 
your choice of input frequencies 
from 5—350 MHz and with any 
output you choose within this 
range. The usable bandwidth is 
approx. 3% of the input fre- 
quency with a maximum of 4 
MHz. Wider band widths are 
available on special order. Al- 
though any frequency combina- 
tion is possible (including con- 
verting up) best results are ob- 
tained if you choose an output 
frequency not more than 1/3 
nor less than 1/20 of the input 
frequency. Enclosed in a 4-3/8" 
X 3" X 1-1/4" aluminum case 
with BNC receptacles, power 
and antenna transfer switch. 

Model 407 price: 

5—200 MHz $42.95, 

201—350 MHz $44.95 

Prices include .005% crystal. 
Additional crystals $5.95 ea. 



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Models 101 and 102 only are 
available enclosed in a die-cast 
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lead-in cable and includes a fil- 
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the cable. Can be used only for 
receiving unless you put a TR 
switch at the antenna. Available 
with your choice of VHF, BNC 
or type "N" receptacles. Espe- 
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tor data curves supplied with 
unit) and guaranteed by our lab 
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in our circuit. Transistor is 
mounted in a socket with gold 
plated contacts. 4 precision 
trimmers make possible tuning 
for optimum desired results over 
a wide range of conditions. We 
supply it tuned for minimum 
noise figure across 50 ohms in- 
put and output resistance. Fully 
shielded in aluminum case with 
feed-thru solder terminals. Sup* 
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Model 102 price: ..... .$19.95. 



UHF 20 dB MIN. GAIN 
3 to 5 dB MAX. N.F 




This model is similar in appear- 
ance to our Model 407 but uses 
2 low noise J-FETS in our spe- 
cially designed RF stage which 
is tuned with high-Q miniature 
trimmers. The mixer is a special 
dual-gate MOSFET made by 
RCA to meet our requirements. 
The oscillator uses 5th overtone 
crystals to reduce spurious re- 
sponses and make possible fewer 
multipliers in the oscillator 
chain which uses 1200 MHz 
bipolars for maximum effi- 
ciency. Available with your 
choice of input frequencies 
from 300—475 MHz and output 
frequencies from 14—220 MHz. 
Usable bandwidth is about 1% 
of the input frequency but can 
be easily retuned to cover more. 
This model is now in use in 
many sophisticated applications 
such as a component of a com- 
munications link for rocket 
launching^. 

Model 408 price: $51.95 

.005% crystal included. 



HOW TO ORDER: 

State model, input and output 
frequencies and bandwidth 
where applicable. Remit in full, 
including sales tax if you reside 
in N.Y. State, direct to Van- 
guard Labs. Prices include post- 
age by regular parcel post. P\>r 
air mail or special delivery in- 
clude extra amount; excess will 
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STUDY GUIDE 



Questions & Answers Part 




27. Define Ohm's Law, How does it 
relate to resistive and reactive impedance? 

Ohm's Law states that the potential 
across an Impedance, in volts, is equal to 
the product of current through the imped- 
ance, in amperes, and the impedance itself, 
in ohms. Stated algebraically, E = IR. 
Ohm's Law applies to any impedance, 
whether resistive, reactive, or a combina- 
tion of the two. When dealing with ac, 
however, rms values for voltage and current 
must be used, and when dealing with a 
mixture of resistive and reactive imped- 
ance, appropriate complex-number arith- 
metic is necessary, (General course, Part I) 

28, Describe ways of equalizing the 
reverse voltage drops across series con- 
nected silicon diodes. 

To equalize reverse dc voltages across 
series-connected silicon diodes, moderately 
high valued resistors should be connected 
in parallel with each diode. 470,000 ohms 
is a typical value. This is enough smaller 
than the reverse resistance of the diode 
itself to equalize the voltage, yet large 
enough not to degrade the diode action. To 
equalize ac voltage spikes, low-value (.001 
/iF) capacitors should be connected in 
parallel with each diode. In many cases, 
both the resistors and capacitors are used. 
(General course, part VII) 

29* What is the maximum legal dc 
power that can be delivered to the final 
amplifier of an amateur transmitter? How 
is this power determined? 

The power applied to the final stage of 

RCH 1972 



an amateur transmitter cannot exceed 
1000W (on some bands, SOW), as measured 
from the voltage and current at the dc 
input to the final stage. If power exceeds 
900W, accurate means of measurement 
must be provided. (General course, part 

VIII) 

30. Define instantaneous power, average 
power, sideband power, audio power, and 
peak envelope power. How is each related 
to the voltage and current that produced 
it? How is each related to the unmodulated 
carrier power? 

Instantaneous power is the product of 
instantaneous voltage and instantaneous 
current, all taken at the same instance. It is 

a fictional concept; current exists only in 
relation to time, so that "instantaneous 
current" cannot be defined. Instantaneous 
power is, however, a useful concept, in that 
it is the highest power level likely to be 
encountered in a circuit; 

Sideband power is the difference be- 
tween average envelope power and unmod- 
ulated carrier power, and is not normally 
determined on the basis of voltage and 
current. 

Audio power is the audio -frequency 
power produced by a modulator, and is the 
product of rms audio voltage and rms 
audio current. This is very close in value to 
sideband power, for a high-level-modulated 
AM transmitter, differing only by losses 
introduced in the modulated amplifier. 

Peak envelope power is the product of 

39 



peak envelope voltage and peak envelope 
current, both measured at radio frequency. 
Average power of a 100% modulated 
AM signal is 1.5 times the unmodulated 
carrier power. Sideband power is half the 
unmodulated carrier power, as is audio 
power required for 100% modulation. Peak 
envelope power is 4 times unmodulated 
carrier power. Instantaneous power may be 
any value between and peak envelope 
power, depending upon the instant chosen. 
(General course, part III) 

31. What is meant by the bandwidth of 
a signal? Compare the maximum necessary 
bandwidth occupied by a CW signal, an 
SSB signal \ a double sideband signal, and 
an ordinary voice signal 

The bandwidth of a signal is the mea- 
sure of the amount of rf spectrum space 
occuped by that signal, and is the differ- 
ence (in hertz) between the highest fre- 
quency component of the signal and the 
lowest frequency component. Assuming a 
band-limited modulating signal in which no 
component is higher than 3 kHz for all 
voice signals, an SSB signal will require 3 

■ 

kHz bandwidth, while both double side- 
band and ordinary AM voice require 6 kHz. 
Bandwidth required by a CW signal de- 
pends upon the transmission speed in wpm. 
Very slow transmissions (1 wpm or so) 
may use as little as 1 Hz bandwidth . 
Normal CW requires approximately 50 Hz. 
High-speed CW may require as much as 250 

Hz, (General course, part IX) 

32. What is neutralization and how does 
it contribute to proper amplifier opera- 
tion? What procedure should be followed 
to properly neutralize an rf amplifier? 

Neutralization is the process of can- 
celing out all undesired feedback from an 
amplifier, and contributes to proper opera- 
tion by preventing regeneration and self- 
oscillation of the amplifier- One method of 
properly neutralizing an amplifier is to 
disconnect all plate and screen voltages, 
leaving grid bias and heater voltages in 
place, and then applying normal input 
signal to the circuit while monitoring the 
output circuit with a sensitive rf indicator. 
The neutralization adjustments are then 
moved through their range until no feed- 



through of energy can be detected. This is 
the point of correct neutralization. (Gen- 
eral course, part VIII) 

33. What are the distinguishing features 
between series-tuned and parallel-tuned res- 
onant circuits? How is the resonant fre- 
quency determined? Define the "Q" of a 
resonant circuit. 

In a series-resonant circuit, the oppo- 
site^value reactances are in series with each 
other, making total circuit impedance 
equal to only the resistive component of 
the tuning components. Impedance is thus 
low at resonance, and current is high. In a 
parallel-resonant circuit, the opposite-value 
reactances are in parallel with each other, 
and the current circulates within this par- 
allel circuit, making external current low 
and impedance high at resonance. The 
resonant frequency is that at which the 
reactances are equal, for series tuned and 
high-Q parallel tuned circuits. For low-Q 
parallel tuned circuits, several different 
frequencies of "resonance'* are defined and 
the choice depends upon the particular 
application. The U Q" of the circuit is the 
ratio of energy stored to energy released 
per cycle, or roughly, the ratio of reactance 
to resistance, (General course, part I IB) 

* i- 

34 r How does an ac power supply 
produce a dc voltage? Distinguish between 
a choke-input and a capacitor-input filter 
and compare their oy mating character- 
istics. What is dynamic regulation and how 

can it be improved? How do the output 
voltages of a full-wave center-tapped and a 
full-wave bridge rectifier compare? 

An ac power supply produces dc output 
by means of rectification, a valving action 
in diodes which permits current to flow 
more readily in one direction than in the 
other, 

A choke-input filter contains inductance 
as its first reactive component, while a 
capacitor-input filter has as its first reac- 
tance capacitance. The choke-input filter 
provides better voltage regulation with 
variations in load than does the capacitor- 
input filter, but produces less output volt- 
age under light load conditions. The capa- 
citor-input filter produces higher output 
voltage, but puts more strain on the recti- 



40 



73 MAGAZINE 



fiers and transformer of the power supply. 

Dynamic regulation refers to changes in 
power supply ' output level caused by 
changes in load current. It can be improved 
by providing additional energy storage (big- 
ger capacitors) in the power supply's out- 
put circuit, or by reducing the power 
supply source impedance by any other 
means such as electronic regulation. 

For the same transformer, the full-wave 
bridge rectifier produces twice the dc 
output voltage of the full-wave center- 
tapped rectifier circuit, because the end-to- 
end voltage capacity rather than the end-to- 
centertap capability of the transformer is 
used. Not ail transformers will withstand 
the high voltage which appears at the 
centertap under the bridge connection, 
however. (General course, part VII) 

35. How do resistors combine in parallel 
and in series to give total resistance? 
Capacitors? Inductors? 

Resistors in series produce a total resis- 
tance equal to the sum of the individual 
values of each resistor in the chain. Induc- 
tors add inductance in similar fashion, if 
mutual coupling is excluded. Capacitors in 
parallel also accumulate value to the sum 
of the individual values. 

Resistors in parallel, capacitors in series, 
and inductors (without mutual coupling) in 
parallel divide the current in such a manner 
as to produce a total value smaller than any 
individual value. The total is the reciprocal 

of the sum of the reciprocals of the 
individual values. (General course, part I) 

36* How does voltage division occur 
across series-connected resistors? Capaci- 
tors? Inductors? 

Across series-connected resistors, an ap- 
plied voltage will divide proportionately to 
the values of the resistors, with the high- 
est-value resistor developing the greatest 
voltage across it. The same is true of 
capacitors and of inductors, so long as the 
applied voltage is ac. The division in this 
case is proportional to the reactance of 
each component rather than the resistance. 
(General course, part I) 

37. What does it mean to connect 
circuit elements in series? In parallel? 

When circuit elements are connected in 



series, the same current flows through 
every element in the circuit. When ele- 
ments are connected in parallel, current 
flowing through one element does not flow 
through any other element, but the same 
voltage appears across every element in the 
circuit. (General course, part I) 

38. What is inductive reactance? Capa- 
citive reactance? How is their value deter- 
mined? How do like reactances combine in 
series? In parallel? 

Inductive reactance is a measure of the 
degree by which the voltage in a circuit is 
retarded in phase with respect to the 
current. Capacitive reactance is a measure 
of the degree by which current is retarded 
relative to voltage. Inductive reactance is 
calculated from the formula X = 2 tt f L, 
and capactive reactance from the formula 
X c = 1/(2 tt f C). Like reactances combine 
in series and in parallel just as do resis- 
tances. (General course, part II) 

39. Describe the transmission character- 
istics of the amateur hands below 30 Mc/s 
(MHz). List several propagation factors 
that influence signal transmission and re- 
ception in these bands. 

Noise, both natural and manmade, and 
ionospheric conditions, which depend 

upon many factors, both strongly influence 

transmission and reception in all bands 

below 30 MHz. 

1.8 MHz: Only groundwave useful during 

day, Range at night limited to 
only a few thousand miles, and 

that only when band is at* its 
best. Noise usually high both day 
and night. 

3.5 MHz: Noise high both day and night, 

especially in summer. Ground 
wave and very short range skip 
(200 miles or so) useful during 
day. At night may reach world- 
wide range but usually limited to 
one hemisphere. 

7.0 MHz: Noise not so severe as on lower 

bands. Similar to 3.5 MHz during 
day but with somewhat greater 
range. At night, worldwide cover- 
age possible and good coverage 
of hemisphere usual, 

14 MHz: Very little noise except during 



MARCH 1972 



41 



solar storms. Long range both 
day and night. Coast-to-coast 
skip during day, worldwide at 
night as usual matter. 

21 MHz: Like 14 MHz, but band not 

usually open during sunspot min- 
ima. At its best, worldwide cov- 
erage during daylight* 

28 MHz: Worldwide coverage for 2 years 

out of 12, useful primarily for 
local work rest of time. MUF 
usually too low for this band, 
but worldwide daytime DX pos- 
sible when conditions are at their 
best. 

(General course, part XII) 

40. List the basic stages of a conven- 
tional superheterodyne receiver and tell 
what function each stage performs. 

The rf amplifier stage isolates the mixer 
stage from the antenna, reducing unwanted 
radiation. The mixer stage converts the 
incoming signal to the fixed intermediate 
frequency. The first (or local) oscillator 
provides a signal to the mixer which selects 
the desired incoming signal. The i-f ampli- 
fier stage amplifies the signal, and provides 
selectivity. The second detector converts 
the signal from intermediate frequency to 
audio frequency, using the output of the 

beat frequency oscillator if necessary (for 
CW and SSB reception). The audio stages 
then amplify the detected signal to the 
desired amplitude to drive headphones or a 
speaker, (General course, part X) 

41+ How is the approximate length of a 
half- wave dipole related to its resonant 
frequency? Compare the operating charac- 
teristics of a half-wave dipole and a ground- 
ed antenna. 

The length of a half-wave dipole anten- 
na is approximately equal to 468 /(resonant 
frequency in MHz) feet. 

The half-wave dipole is electrically bal- 
anced; the grounded antenna is not. Feed 
impedance of a half-wave dipole in free 
space is 73£2; that of a grounded antenna is 
approximately 3 5 £2. The half-wave dipole 
has a directional pattern, with nulls off the 
ends of the wire; the grounded antenna is 
omnidirectional. The half-wave dipole pro- 
duces high-angle radiation; the grounded 



antenna's radiation is concentrated at low 
vertical angles. In general, the half-wave 

dipole provides better short and moderate 
range coverage, while the grounded anten- 
na provides greater range for DX, (General 
course, part XI) 

42. What do high- and low- pass con- 
stant-k filter circuits using balanced and 
unbalanced ir-and T-sections look like? 




Fig. 1, Constant-K unbalanced 71-section low-pass 
filter. 




^TYYV\ 



Fig. 2. Constant-K unbalanced T-section low- 
filter. 




Fig. 3, Constant-K balanced Tt-section low-pass 
filter. 




Fig. 4. Constant-K balanced T-section low-pass 
filter. 




Fig, S m Constant-K unbalanced T-section high 
pass filter* 




Fig. 6. Constant-K unbalanced TT-section high-pass 
filter. 



42 



73 MAGAZINE 




Fig, 7. Constant* K balanced T-section high-pass 
filter. 




Fig. 8. Constant- K balanced 71-section high-pass 
filter. 



43. How can amateur equipment he 
pro tec ted fro m Ugh t n ing dis charge ? 

By means of a grounding switch. (Gen- 
eral course, part XI) 

44. What are the basic stages of a single 
sideband (SSB) receiver and transmitter 
and what purpose does each serve? 

Basic stages of an SSB receiver are the 
first mixer, first oscillator, if strip, second 
mixer, second oscillator, and audio sec- 
tions. The first mixer converts the in- 
coming SSB signal to an SSB signal at 
intermediate frequency, by means of the 
output of the first oscillator. The i-f strip 
amplifies this signal, and provides the 

necessary selectivity. The second mixer 
(sometimes called a product detector) uses 
the output of the second oscillator to 
demodulate the SSB signal into audio, 
which is then amplified by the audio 
section, 

Basic stages of an SSB transmitter are 
the SSB generator, the frequency deter- 
mining circuits, and linear amplifiers. With- 
in the SSB generator are included audio 
circuits and mixers, to generate an SSB 
signal at fixed frequency. This fixed fre- 
quency SSB signal is then mixed with a 
variable frequency signal to produce the 
final output signal, which is then amplified 
by linear amplifiers. 

The transmitter and receiver are almost 
exact inverses of each other, which has led 
to the development of transceivers which 
share common stages between transmitter 
and receiver functions. (General course, 
part X) 

MARCH 1972 



45. List the three main classes of ampli- 
fier operation and explain the use for 
which each class is best suited. 

The three main classes are A, B, and C. 
Class A amplifiers are best suited when low 
distortion is required, as for receivers and 
hi-fi amplifiers. Class B amplifiers provide 
higher efficiency and are best suited for use 
in portable and mobile equipment where 
long battery life is essential. Class C ampli- 
fiers are best suited for high-power if 
amplifier application where their distortion 
can be tolerated, (General course, part VI) 

46. What are **images "in a receiver? 

Images are spurious responses in a super- 
heterodyne receiver caused by the presence 
of an unwanted signal on the "wrong side" 
of the local-oscillator signal. If the receiver 
is designed to make use of the "input- 
minus-local -oscillator" difference fre- 
quency as its i-f, the * local-oscillator- 
minus-input" difference frequency is an 
"image," (General course, part X) 

47. What is meant by "fla stopping" of 
a single sideband signal and what are some 
possible causes of it? 

Flat-topping is a form of distortion in 
which the output signal's peaks are flat- 
tened rather than being reproduced accu- 
rately. It may be caused by excessive level 

of input signal, or by incorrect bias or 
loading in the amplifier stage- (General 
course, part VI) 

48. What does grid current flow in a 
class A amplifier indicate? 

In most class A amplifiers, grid current 
flow indicates incorrect operating condi- 
tions. The usual cause is severe overdriving 
of the input. It may also be caused by a 

failure of grid bias voltage. (General course, 
part VI) 

49. Briefly discuss how a multiband 
"trap" antenna operates. 

A multiband trap antenna includes par- 
allel-resonant tuned circuits at critically 
spaced points in an otherwise normal half- 
wave dipole. At the frequency at which the 
trap circuit is resonant, the tuned circuits 
act as insulators and disconnect the ends of 
the antenna, so that the inner portion of 
the antenna acts as a half-wave dipole at 

43 



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this frequency. At lower frequencies, the 
net reactance of the trap circuits is induc- 
tive, and so the traps act as loading coils to 
electrically lengthen the wire. The full 
length of the wire (as electrically length- 
ened) then acts as a half-wave dipole at the 
lower frequency. By adding additional 
pairs of trap circuits, and by proper adjust- 
ment, the antenna can be made to cover all 
amateur HF bands. (General course, part XI) 

50. How can the power input to the 
final amplifier of an SSB transmitter be 
determined? 

The power input to the final stage of an 
SSB transmitter is determined by mea- 
suring plate voltage and plate current with 



dc meters having a time constant of at least 
¥4 second, and using the highest values 
indicated by the meters under normal 
modulation. (General course, part VIII) 

51, Compare the operating features of 
the grounded grid and grounded cathode 
amplifiers. 

Input of the grounded grid circuit is low 
impedance; that of the grounded cathode is 
moderate. Output impedance of the 
grounded grid is high; that of the grounded 
cathode is moderate. Current gain of the 
grounded grid is less than 1; that of the 
grounded cathode is moderate. The 
grounded cathode circuit reverses phase 
between input and output; the grounded 
grid does not. (General course, part V) 

52. How is the bandwidth of an FM 
signal related to the bandwidth of the 
modulating audio signal? 

The bandwidth of an FM signal is 
related to the bandwidth of the modulating 
audio signal in a complex manner which 
depends upon the modulation index. At 
low values of modulation index, when only 
the first pair of sidebands is significant, the 
FM signal's bandwidth (like that of an AM 
signal) is twice that of the modulating 
signal, As the modulation index increases, 
the bandwidth increases also. At a mod- 
ulation index of 5 (used in commercial FM 
broadcasting), the bandwidth is 10 times 
that of the modulating signal. (General 
course, part IX) 

This concludes the study list questions 
for the General class license. These ques- 
tions also apply to the Technician and 
Conditional class license examinations, 
which embody the same technical content 

as the General class. 

. , . Staff 




Moving? Please let us know. 



44 



73 MAGAZINE 



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or DC; and 6 ranges measure resistance from 0.1 
ohm to 20 megohms. Input impedance is approx. 
1000 megohms on 2V range, 10 megs on higher 
ranges, with overload protection built-in. Decimal 
point automatically placed with range selection. 
Front panel light indicates overrange, DC calibra- 
tor furnished. An internal circuit and unique trans- 
fer method allow accurate ACV calibration. 
Solid-state design with cold cathode readout tubes 
and memory circuit assure stable, non-blinking 
operation- Kit includes standard banana jack con- 
nectors complete with test leads. Put it together 
in about 15 hours for a lifetime of precision per- 
formance. 




New Heathkit 

5" Triggered Sweep Scope . . , 



$2J9«' 



• DC-10 MHz response — Triggered 
Sweep 

• 50 ns sweep rate with magnification 

• AC-DC coupling 

Maximum flexibility In a general purpose scope, at 
a price to fit any budget . . . the new Heathkit IO- 
103 is a radio amateur's dream come true! Big 
6x10 cm screen with lighted graticule for easy, 
accurate measurements. DC-10 MHz ±3 dB re- 
sponse with less than 50 ns rise time on vertical 
channel. Horizontal expansion gives x2 magnifi- 
cation ±5% for a 50 ns/cm sweep rate. Triggered 
sweep, too, with selection of either normal or au- 
tomatic modes. Other features are switch con- 
trolled AC-DC coupling; provision for external 
triggering signals and horizontal deflection signal; 
front-mounted connectors for vertical inputs and 
1V peak-to-peak signal for checking calibration; 
120/240 VAC operation. Put this budget-minder to 
work in your ham shack ...now. 

Kit IO-103, 37 lbs . . ,. . .229-95* 



HEATHKIT 



! HEATH COMPANY, Oept 11-3 



Schlumberger 



Benton Harbor, Michigan 49022 



I □ Enclosed is $. 



Please send model(s). 



Name. 



Kit INI-102, 9 lbs. 



.229.95* 



I 

i 

I ] Please send FREE Heathkit Catalog, 
I 

i 

i 
i 

i 
i 
• 

i 

i 



plus shipping. 



I 
I 
I 
I 
I 
I 
I 
I 
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I 
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I 
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I 

Prices & specifications subject to change without notice, i 
*Marl order prices; F.0.B, factory, AM-262 | 



Address, 
City 



.State. 



-Zip. 



m 








AMATEUR RADIO 
GENERAL 

LLMou 

LICENSE 

STUDY 

GUIDE 




AMATEUR 

RADIO 

ADVANCED 

CLASS 

LICENSE 

STUDY 

GUIDE 



AMATEUR 

RADIO 

EXTRA 
CLASS 




STUDY 
GUIDE 






A The Novice Class Li- 
cense Study Guide has not 
yet been published m 73 or 
in any other magazine. 
This book contains all the 
basic technical information 
need to pass the Novice 
License with flying col- 
ors. . .and is invaluable as a 
basic text for understand- 
ing the General Class Study 
Guide. Profusely Illustrated 
and so clearly written that 
just reading it is enough to 
permit most applicants to 
pass their exam. $3.95 
value. 



B The 73 General Class 
Study Guide has helped 
thousands to easily pass 
their General License the 
first time through. At $9 a 
whack, isn't it foolish not 
to hedge your bet with this 
comprehensive and simple 
book? No other study 
guide is as complete or as 
easy to read. None. A 
$4.95 value. 



C The Advanced Class 
Study Guide has proven to 
be the only compfete text 
for preparing to pass the 
Advanced Class license 
exam. Never before has 
radio theory been made so 
simple. After just reading 
this book it is almost im- 
possible to fail that exam. 
And remember that in ad- 
dition to the trouble of 
going to the FCC to take 
that exam, there is a little 
matter of $9 you have to 
ante up. Why take a chance 
on failing? $6.95 value. 



D The Extra Class License 
Study Guide makes all that 
complicated electronic the- 
ory seem simple. A little 
study with this book and 
you will be ready to face 
the FCC examiner with 
'confidence. A $4.95 value! 



HANDBOOK^ 



■ mJLi Z~^ !•■ « 1 1 p > ■ 



Hill 



II DWB 






FZM ■=■ 



H(in 



MCAFNJ 



Cliff 



GR9M 



Ha 


HHfDL 


FU 




i 


fliac wu KK3NK 


1 *«>:*:» 1 





I 

'fivi bulletin 




for the 
AMATEUR 









N!CDMtf:Tfl|jf 
ZlUK 



E The 73 DX 
handbook has every 
DX aid you could 
hope for. . .QSL 
Bureaus, postage 
rates worldwide, 
DXCC and WTW 
country lists and re- 
cord pages, maps of 
many areas of the 
world with prefixes, 
plus a complete 
wall-sized world 
map with each 
book? It is profusely 
illustrated with pic* 
tures of many of the 
top DXers, plus art- 
icles on working DX 
on the different 
bands. There are 
great circle bearing 
maps and charts, 
and more. . .more 
. . ,more. 



F The FM Anth- 
ology has reprints of 
all the articles and 
technical data from 
the early issues of 
the FM Journal. No 
FM library is com- 
plete without this 
data, much of it just 
not available else- 
where, $5.95 value. 

G The BEST of 
FM is a compilation 
of the best articles 
that appeared in the 
FM Journal from 
March 1968 through 
June 1969, the last 
of the magazine. 
Read the extremely 
controversial Chron- 
icles of 76. Plus do- 
zens of technical 
and circuit articles 
a v a i lab le nowh ere 
else. $4,95 value. 

H Transistor Pro- 
jects for the 
Amateur is cram- 
med with over 40 
interesting construc- 
tion projects cover- 
ing receivers, con* 
verters and transmit- 
ters, many in the 
VHF region. If you 
like to build you 
will blow your mind 
over this book. 







GET ONE BOOK FREE WITH EACH DIFFERENT SUBSCRIPTION. 
GET THREE BOOKS FREE WITH EACH LIFE SUBSCRIPTION. 

Accept ONE BOOK FREE with our compliments for each different $6 subscription you enter. Free 
Gift Books can be sent to each subscriber or to the donor. One gift book per $6 subscription, wherever 
they go. All subscriptions will be entered to start with February 1972 unless otherwise noted* On 
renewafs or extensions of subscriptions please include the address label from the magazine wrapper or 
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extra doMar per one year subscription. 

Offer expires April 30, 1972 
Please enter subscriptions for the following, starting with the February 1972 issue. 



That's right, all you have to do is buy 
a one year $6 subscription to 73 and you 
are eligible for a free book (postpaid) of 
your choice or a set of back issues (FOB 
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Fine, no trouble whatever, just buy a 
little old gift subscription for a friend or 
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Can you buy two years for $12 and 
get two books? No, sorry about that, but 
the whole purpose of this unusual offer is 
to increase the circulation of 73, not to 
just give away a few thousand books free 
of charge. We know that once an active 
amateur starts reading 73 he has a hard 
time ever being without it again and so, 
though we pay dearly for that first 
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come renewal time. And keep in mind 
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the better magazine we can give you. 

Over 3000 great articles have appeared 
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1960-1964 (I), 1965-1967 (II), and 
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bundles are put together by illiterate 
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magazine staffs and thus there is no 
possibility of our guaranteeing any parti- 
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packages (12 different back issues in each 
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ECHNICAl 




ROUP 



Tile Technical Aid Group is a group 
of hams who have indicated a willing- 
ness to share their knowledge and 
skills with others. They have volun- 
teered to be of service to fellow hams 
and do so without compensation, If 
you have a technical question, look 
over the list to see who has competen- 
cy in the area of your question. For 
many of the TAG members, descrip- 
tions of all areas of expertise would be 
lengthy, so an abbreviated description 
is given. When stating your problem t 
give as much information as possible 
and clearly state the difficulty. En- 
close a SASE for reply. 

For those hams who have a desire 
to share, the TAG is the thing for you. 
Send a brief note requesting the mem- 
bership form, fill it in and send it 
back. It asks a few questions about 
your qualifications, and there is a 
check-list to indicate your fields of 
competence. These cover all modes 
currently used by hams, antenna de- 
sign and theory, transmitter and re- 
ceiver design for HF, VHF, and UHF, 
logic, ICs, general help, and other 
areas. As more members are added, 
their names and addresses will be 
published. 

This list is not complete, but repre- 
sents those former TAG members who 
have responded to a recent mailing 
and have expressed a desire to con- 
tinue in the program. Comments from 
them indicate that they have enjoyed 
helping and all have been contacted 
frequently for advice, 

Robert Perlman WB2VRW t 3 
Josten Place, Hudson NY 12534. Elec- 
trical engineering student. Will help 
with Novice transmitters and receiv- 
ers, and any help for beginning hams- 

Thomas Laffm WIFJb, Box 133, 
Hillsboro NH 03244. Radio communi- 
cations technician. Special aid to ex- 
CBers and those who need terms in 
easily understood terms: aid to Nov- 
ices and Techs interested in MARS, 
RACES, CD, and CAP; how to build 
and scrounge parts; assistance on ham 
history, ATV. microwave, and general 
help. 

Theodore Cohen W4UMF, 8603 
Conover PL, Alexandria VA 22308. 
Geophysicist, Specially prepared to 



answer questions about SSTV and 
ATV. 

/ Bradley Flippin K6HPR, 116 
Montecito Ave., Apt, M., Monterey 
CA 93940* Electronic engineer. Help 
with RTTY, data processing and pro- 
gramming, general. 

Ira Kavakr WA2Z/R. P.O. Box 54, 
Flatbush Sta., Brooklyn NY 11226. 
Electrical engineer. Assistance offered 
in theoretical aspects of electricity 
and electronics from dc to UHF, 
design of equipment, computer pro- 
gramming, and signal circuit (failsafe) 
design. 

Jon Teich WB2JAE, 22 Olden Rd., 
Edison NJ 08817. High school stu- 
dent. Novice and others, transmitter 
and receiver problems, logic, and gen- 
erai. 

David Felt WB6ALF, P.O. Box 261, 
Sierra Madre CA 91024. Electronics 
engineer. Qualified help in logic , digi- 
tal and analog design, solid state, AM 
and TV. 

Robert Groh WA2CKY, 65 Rox- 
borough Rd., Rochester NY 14619, 
Communications engineer. Bob can 
lend a hand in HF and VHF transmit* 
ter and receiver design as well as 
solid-state logic and digital techniques, 

Cart Milter WA6ZHZ 334 Paragon 
Ave^ Stockton CA 95207, Computer 
technician. Carl's specialty area is 
solid-state QRP. 

George Daughters WB6AIG. 1560 
Klamath Dr., Sunnyvale CA 94087. 
Research associate. HF transmitter 
and receiver, SSB, and solid state, are 
George's fields. 

D. Hausman VE3BUE, 267 North- 
crest PI , Waterloo, Ontario, Canada. 
Student. Novice transmitter and re- 
ceiver problems as well as logic, digital 
techniques and ICs. 

Hugh Wells W6WTU, 1411 18th St., 
Manhattan Beach CA 90226. Elec- 
tronics instructor. Hugh can help with 
AM, Novice problems. VHF-UHF re- 
ceivers and converters, solid state, test 
equipment, FM and repeaters, and 
genera! help. 

Charles Hill WA 7LQO, 4005 Camp^ 
bell St., Baker OR 97814. Student. 
TV, Novice transmitter problems, and 
logic. 

John Perhay WA&DGW. Route 4. 



Owatonna MN 55060. EE technician. 
John will help with RTTY, AM, SSB, 
Novice gear, HF transmitters and re- 
ceivers, solid state, ICs, and test equip- 
ment. 

Jim Jindrick WA9QYC, 801 
Florence Ave., Racine WI 53402. Con- 
sulting engineer. General help as well 
as HF. VHF, and UHF antennas, 
transmitters, and receivers. 

William Welsh W6DDB, 2814 Em- 
pire Ave., Burbank CA 91504. Elec- 
tronic engineer. Beginner's problems, 
code instruction, theory and regula- 
tions. 

Ken Knecht K8VNT t Box 39, Clin- 
tondale NY 12515. Television en- 
gineer. TV, logic, and digital tech- 
niques. 

Tom OHara W60RG* 10253 E. 
Nadine St., Temple City CA 91780. 
Communications engineer. RTTY, 
TV, AM, SSB, VHF antennas, trans- 
mitters and receivers for HF through 
UHF. solid state, and general help. 

Bruce Creighton WA5JVL. 2517 
Metairie Ct„ Metairie LA 70002. Elec- 
trical engineer. Antennas, Novice 
problems, solid state, logic, digital 
techniques, test equipment, and gen- 
eral help, 

Tom Borok WB2PFY 215-33 23 
Rd„ Bayside NY 11360. Student. 
Tom is especially qualified to help 
Novices with their problems with 
transmitters and receivers, HF and 
VHF antennas, HF receivers, test 
equipment, and surplus, Morse code 
instruction. 

Roger Tay lor K9ALD. 2811 
William St., Champaign 1L 61820. 
Engineer. Roger is adept with AM, 
SSB, antennas, solid state, logic and 
digital techniques, ICs, test equip- 
ment, and other general help. 

Orris Grefsheim WA6UYD, 1427 
W. Park St., Lodi CA 95240, TV 
technician. Orris is capable of assisting 
in all fields of amateur work, DC 
through UHF, logic as well as Novice 
help. 

John Allen K1FWF, 1 1 2 Edgemoor 
Lane, Ithaca NY 14850. Technical 
director. John's areas of assistance are 
VHF and UHF antennas, receivers, 
and transmitters, solid state and digi- 
tal techniques, ICs, and SSB, 



48 



73 MAGAZINE 



Putting The ARC -3 On Two 




For the amateur who wants a step up 
from the lunchbox class of 2 meter 
equipment (no slurs intended) the 
AN/ARC-3 offers an excellent low-cost 
opportunity. A moderately stocked junk- 
box and a little scrounging can put the 
units on the air for an additional $10-15 
cash outlay. 

The ARC-3 system consists of five basic 
units: receiver, transmitter, control box, 
antenna, and dynamotor assembly. Only 
the transmitter and receiver are used in this 
conversion. Mating plugs are a matter of 
preference and cost, For fixed work a 



Neaie C. High tower WA4NAH4 
160 Fourth Street NW 
Atlanta GA 30313 

scheme is presented to avoid the need for 
these plugs. For a mobile installation, it is 
probably advisable to purchase these units 
if they are available. A good schematic is 
essential for this work, as is the case with 
most conversions. If one is not available 
from the supplier of the units, Bill Slep 
Co. 1 will supply separate schematics of the 
units. The price is $1 each. 

Very few amateurs have the same needs 
or desires in equipment. Thus this conver- 
sion is presented as a number of "subcon- 
versions/* Almost all are independent of 
each other. One can tailor the conversions 



MARCH 1972 



49 



to suit his particular application by instal- 
ling the features most useful to him* 

Before starting the conversion, it is a 
good idea to have a rough idea of how the 
system works. Figure 1 shows a block 
diagram of the receiver system. The layout 
is conventional except for the automatic 
tuning mechanism and the harmonic gen- 
erators. All frequencies (100-156 MHz) 

■ 

are tuned in 7 bands using 8,0 to 8.5 MHz 
crystals on their II Mi to 1 8th harmonics. 
The harmonic generator chain is fairly 
narrowbanded; therefore, when it is de- 
tuned slightly from its center (the stages 
are not tuned to integral multiples of the 
crystal frequency), the output drops rap- 
idly. Once a new channel is selected, relays 
change the appropriate crystal and a con- 
trol tube senses that the harmonic chain is 
detuned. The tuning motor is started, 
turning the tuning mechanism. Normally, 
the tube would cause the motor to tune to 
the next harmonic and shut off when the 
chain output equaled the I4V reference. 
But if the previous channel was on Mi 
12th harmonic and a frequency using the 
17th harmonic was desired, the system 
would stop at the next harmonic (13th) 
instead. To prevent this the coding wheels 






HF AMP 



f 



MtKEF *- * 



UK 



* 



,-.v; : 



AMP 5 



-< 



1 — i*- 






i*V «E s 'E='i 



GX&-© 6 



coaittG *M£f 



i*QrO*» 



Fig. 2. Block diagram of receiver system. 



are added, They select the proper harmonic 
and "kill" the harmonic chain output until 
the tuning mechanism is in the proper 
range, Then the output of the harmonic 
generators is applied to the sense tube for 
exact tuning. 

The transmitter block diagram is shown 
in Fig, 2, Since it uses crystals from 5-5 to 
8,6 MHz, all on the 18th harmonic, it is 



V 



XTAL 
OSC 



HARMONIC 
GENERATORS 



RF 

OUTPUT 



&- 



MOTOR 
14V REFERENCE 



SENSE 
TUBE 



T 



MODU- 
LATOR 

~ J 



TONE 
OSC 



AF 
AMP 



■*— Qmc 



Fig t 2, Block diagram of transmitter. 

only necessary to determine when the 
multiplier and output stages are in tune. 
The tuning mechanism is basically the same 
as that of the receiver except that the 
coding wheels are not employed. 

Converting the Receiver 

Unless it is to be used in some config- 
uration very similar to the original, "the 
following changes are recommended for 
the receiver: 

1. Rewire the filament string for 
I2V 

2. Provide an external B+ supply 

3. Add an external audio gain con- 
trol 

4„ Add external speaker (or head- 
phones) 
Two other features may be added: 
5, Manual (continuous tuning) 
6- Rf gain control 

Filament String Conversion 

The 24V filament lines may be con- 
verted for us on 12V (ac or dc) by the 
following procedure: 

Identify R-201 (252ft). It shunts the 
filament of V20I : one side is connected in 
five leads, two on one post, three on 
another. The posts are jumpered together. 
Remove the jumper and all five wires. One 
wire goes back to V201. Reconnect it to 
the R201 post and add a jumper from this 
post to ground. Another wire goes to V205 
through C206 ? the center feed thro ugh ca- 



50 



73 MAGAZINE 



pacitor beside the tube. Identify this lead 
with an ohmmeter and attach it to the 
R201 post. Attach the other three wires to 




TO V20I 



R20I 



TO V207 



R20I 



> 



f77 



ORIGINAL 



MODIFIED 



Fig. 3. Detail of 12V Filament conversion. 

the now empty "other" post. This change 
is described in Fig, 3. Identify the three 
posts on the rear of the brake, K202, 
which is located near the motor gearbox 
assembly. Two white wires are connected 
to the centerpost. One goes to pin 8 of 
V216. Connect this wire to some nearby 
groundpost. Replace the other wire Now 
run a new wire (20 AWG or larger) as 
indicated in Table I, 

Table I. ARC-3 Wire Routing 



From 


Pin 


To 


Pin 


V216 


7 


V215 


8 


V215 


8 


R291 


7 


R291 


7 


V212 


7 


R291 


7 


V207 


7* 


V207 


7 


V203 


3 


V216 


7 


V209 


4«« 



*lf the filaments are to run on ac, disconnect 
R225 from pin 7. 
** This is best done at a post near V209 to 
which R202 is connected. 

Remove the lead from pin 2 of V207 
and connect it to pin 7. Ground pin 2. If 
dc filaments are to be used, the conversion 
is now complete. The filament supply is 
now pin 1 2 of P202. Remove R291 . 

For ac operation (and utilization of the 
automatic timing) a small dc supply must 



i? VAC 





Fig. 4. Power supply for autotune operation. 



MADE IN U.S.A. 

The First AM-FM 

Solid-State Transceiver 

For Two Meters 

No longer is it necessary to choose between 
AM and FM on two meters. Now you can have 
both in one compact unit. Join the gang on 
the new FM repeaters yet still be able to "rag 
chew" with old friends either AM or FM any- 
where in the two meter band. 

COMPARE THESE FEATURES 

TRANSMITTER: 

■ Built-in VFO (Frequency converted for stability) 
AM and FM both crystal and VFO 
Four transmit crystal positions (8 MHz) 
12 watt input AM and FM 
High level transmitter modulation on AM 
Bandpass coupled transmitter requiring only final tune 
and load 

Three internal transmit crystal sockets with trimmers 
for netting 

One transmitter crystal socket on the front panel 
Deviation limiting 

■ 146.94 MHz crystal included 

RECEIVER: 

a Double conversion 

■ Crystal controlled first conversion 

■ MOS FET receiver front- end 

■ Integrated circuit Jim iter and discriminator for FM 

a Envelope detector and series gate noise clipper for AM 

■ Built-in squelch for both AM and FM 

GENERAL: 

■ Separate transmitter and receiver tuning 

■ Built-in 115VAC power supply 

■ Direct 12VDC operation for mobile or portable operation 

■ Optional portable rechargeable snap-on battery pack 
available 

■ "S" Meter also used for transmitter tune up 

■ Military style glass epoxy circuit boards 

■ Anodized lettering and front panel 

■ Baked epoxy finish on the cabinet 

■ 47 transistors, 22 diodes, 1 integrated circuit 
m Dimensions: 10% "W x 6tt"H x 7y 2 "D 

Warranty — 90 Days Parts and Labor 



I 



The CTR-144 is available at your 
DEALER or order FACTORY DIRECT 

COMCRAFT COMPANY 

P.O. BOX 266— GO LET A. CALIF. 93017 

Write for more information or 
use READER SERVICE 




MARCH 1972 



51 






I ^- 






HETP^ 



Potke and public safety organizations depend on reliability 
and performance. To meet these needs in communication 
crystals, more and more systems are specifying SENTRY 
CRYSTALS, We are proud to be working with the Detroit 
Police Department as ar\ exclusive supplier of communication 
crystals for their various requirements. 



If you haven't received a copy of our new 1972 
Catalog of Precision Quartz Crystals and Elec- 
tronics for the Communications Industry send for 



your copy today 



a 



Buy the Best" 



SENTRY MANUFACTURING COMPANY 

Crystal Park, Chkkasha, Oklahoma 73018 

PHONE: 405-224-6780 / TWX 910-830-6925 



FRONT OF RECEIVER 



V-207 



o ©«■-• 



Table II. ARC-3 Voltage Requirements 




V-201 



29 yF, 25V 

TERMINAL STRIP 



Function 
Filament 
Receiver B + 
Transmitter B+ 

Relays 



Power 

12V t 7.SA 

225 V, 100 mA 
410V, 325 mA 
28V. 500 mA 



Table IL ARC-3 Voltage Requirements 



TUNING CAPACITOR 
ASSEMBLY 



Fig. 5. Detail of auto tune power supply mounting. 



be added to produce the 14V reference, (If 
the filaments are ac powered and the 
autotune is unused, remove R225.) This 
reference voltage was originally derived 
from the center of the filament supply for 

V207 and V210. A peak rectifier and 
voltage divider may be added as shown in 
Fig. 4, The diode can be almost any type. 
The supply is mounted on a 3-terminal 
strip between V201 and V207 (Fig. 5). The 
ground lug is mounted under one of the 
bolts securing the tuner assembly to the 
chassis. 

External B+ Supply 

The supply shown in Fig. 6 is for both 
the transmitter and receiver. For those 
contemplating a mobile supply, the data in 
Table II should be helpful. 



To power the tuning motors, it is 
necessary to have a supply capable of 
delivering about 6A at 28V- Any less 
capacity will cause the autotune me- 
chanism to malfunction. Thus automatic 
tuning for fixed (ac) work is not recom- 
mended. 

The power transformer used was scrap- 
ped from an old (very old) television. It has 
a centertapped 12V winding to handle the 
necessary current. An exact replacement is 
not known> but only transformers from 
"monster" TVs will work. Instead, for 
most work it would probably be better to 
use two transformers. The inductors were 
removed from old TVs. As can be seen, the 
parts used are mostly junk, so feel free to 
substitute. 

Connection to the receiver and trans- 
mitter was effected by removing the pin 
connectors from an octal socket. The older 
"wraparound" type were employed, If 
these are not available, most hobby shops 
carry small brass tubing which could be 



TO RCVR P-202 
PIN NO. 
** 12 




TO KMTR PH03 
PIN NO. 



01,02-500 *J»A, ! KV 
D3-2A, SO PIV 
Tl-S«« T#it 
T2H2V, 2A SECONDARY 
KI-24V DPOT RELAY 



Fig. 6. Transmitter and receiver power supply. 



MARCH 1972 



53 



The power supply used at WA4NAI was 
adapted from use on another project, A 
supply using a different layout would be 
more practical and esthetically pleasing. 

Audio Gain Control 

Disconnect C294 from pin 1 of V216. 
Remove R28G, C296, R289, and R290 
from the other side of C294. The last three 
components are mounted on the rear of 
the chassis on a point-to-point board. 
Remove R281 and R284. Add the audio 
gain control as shown in Fig. 7. One of the 
points cleared by the removal of C294 may 
be used as a tie point. If the leads are to be 
extended beyond the chassis, it would be 
wise to shield them. Moving one side of 
C294 significantly increases the gain of the 
stage. 

External Speaker 

Two output impedances are available 
for a speaker at pins 16 and 17 of P2Q2. 
Pin 16 is 50^ and pin 17 is 600£2. The 
600fi output could be used directly with 
headphones. A 600H line-to-voice-coil 
transformer may be installed to match a 4 
or 8£2 speaker. One might also use a 45 fi 
speaker directly across the 50U output. 
Those wishing to replace the output trans- 
former can use the Stancor A-3879. If the 
12A6 tube is defective or missing, it can be 
replaced with the more common 12V6. 
Tuning 



1/2 V-2I5 



C-»4 



ARC-3 was originally designed for 
crystal-controlled reception on 8 different 
preset channels. If channelized operation is 
desired, all that is necessary is to supply 
28V to the A+ terminal of P202 and 12V 
to pin 12. Attach a switch as shown in Fig. 
8 and install crystals as determined by the 
following formula; 

Where :F C = xtal freq, MHz. 

F c = (F -12)/n F = operating freq, MHz, 

n = harmonic (8.0 <F C <8.5) 

Manual Tuning 

Continuous tuning requires the conver- 
sion of the crystal oscillator to a tuned - 
grid-tuned-plate oscillator. In addition, one 
must arrange some method of keeping the 
rf and multiplier stages in tune. Severa 




^ 



r 

*" 277 l l MEG 
VOL 

(MOVE) 




AUDIO STAGE MO0IFJCATIOW5 

Fig. 7. Installation of audio gain control 

different schemes are possible, but the one 
presented seems the best for simplicity and 
versatility. The automatic tuning and relay 
logic are simply left unused by a combina- 
tion of electrical and mechanical methods. 




* 9 



RECEIVE* CHANNEL 
SELECTOR SWITCH 



Fig. 8. Hookup for channelized reception. 



Oscillator Conversion 

Conversion of the oscillator involves 
replacing the crystal with an LC circuit 
tuned to roughly 8 MHz, adjustable over 
the desired range. Details of the circuit are 
shown in Fig. 9. To begin the conversion, 
remove the wire to pin 6 coming from the 
relay bank. LI is mounted in the now 
vacant hole near V201. CI is mounted on 
the front panel (over the old relay cavity). 
Connecting leads are threaded through the 
holes in the crystal sockets. 

Alignment of the tunable oscillator can 
be done with reasonable accuracy on the 
air. Choose a signal near the bottom of the 



— 1 v-tot 




Fig. 9, Conversion of crystal oscillator to VFO. 



54 



73 MAGAZINE 



band of known frequency and set the 
tuning capacitor to about 90% meshed. 
Now tune in the signal with the slug of LI 
(it may be necessary to add or remove one 
or two turns). Three signals spotted across 
the band should give a reasonably accurate 
dial scale. Of course, a better job can be 
done with a signal generator. 

In a mobile installation, it might be 
desirable to tune the oscillator remotely 
with a varactor, A suggested hookup is 
shown in Fig, 10 + 

Continuous Tuning 

For fixed station use, a shaft and gear 
system are installed in the old squelch level 
access hole, and the control is moved to 
the rear of the chassis above the 12H6 
detector. Begin by turning over the receiver 
and loosening the front, removing five 
screws on each side. Press the brake me- 
chanism manually and turn the tuning 
shaft so that both setscrews designated in 
Fig. 1 1 can be reached with a splined 
wrench without again turning the shaft 
(this assures that alignment will not be lost 
between the tuning capacitors and the 
front dial). If the screws don't come out 
easily, heat them with a soldering iron and 
they will almost fall out. Carefully slide the 
front loose and remove the squelch control 
and bracket, Disconnect the control and 
mark the leads so that they can be ex* 
tended to some other location. Drill out 
the brad which holds the slide assembly 
covering the squelch access hole. Mount an 
old potentiometer bushing in the access 
hole (ream it slightly). Figure 12 shows the 
mechanical details of the conversion. The 
gears used in this conversion are from the 
depths of a friend's junkbox. One could 
also use gears from an erector set (write the 
company or bargain with Junior), a slot car 
supply center, or belt and pulleys from an 

REGULATED 
VOLTAGE | ME6 




IOK 



V-201 



DI-25 pr VARACTOR DIODE 

Fig. 10. Remote oscillator tuning circuit using a 
var actor. 




Fig* 11. Photo of manual tuning conversion. 



old phono motor (use your imagination). 
Certain surplus equipment such as old 
bombing navigation devices is often a good 
source of small gears. Finally remove or 
loosen the getscrews shown in Fig. 1 1 . 

Tuning the receiver is like tuning a 
communications receiver having a preselec- 
tor. Choose the approximate frequency of 
operation with the rf stages then tune the 
signal with the oscillator. Finally peak the 
RF stages. 



DIAMETER AS 
NECESSARY 
TO FIT GEAR 




DIAMETER AS 
NECESSARY 



3/16 in. FLEXIBLE SHAFT 



L 



SETSCREW 



1/4 m BRASS 
OR STEEL ROD 



PRESS FIT 



Fig. 12. Mechanical details of manual tuning con- 
version, 

Rf Gain Control 

An rf gain control may be added with- 
out too much trouble. The hookup is 
shown in Fig. 13. The pot is a half-watt 
unit, and any value near 25 kH will do. 

Begin by removing the cover plate over 
the section of the tuner assembly which 
mounts V208 and V:0 C >. Carefully lift the 
ground end of R236 and add a one-lug 
terminal strip directly outside the side 
plate. Extend the ground end of R236 to 



MARCH 1972 



55 



the lug. One can now run a wire from this 
lug to the front panel. 

Transmitter Conversion 

The transmitter involves somewhat less 
conversion than the receiver, since the 
output is left crystal-controlled. The bulk 
of the tabor involves attaching a front 
panel and extending control leads to it. 
Additionally, a manual peaking feature for 
the rf stages is presented to avoid use of 
the automatic tuning motor and its accom- 
panying 28V high-current supply. Provi- 
sions are made for a relative output indi- 
cator and a 1 2V filament supply. 

12V Filament Supply 

The transmitter filaments draw about 
4.5 A at I2V. In many cases, a transformer 

capable of handling this load is expensive. 



v-zoe 



C-250 




25K 
RF GAIN 



Fig. 13. Addition of rf gain conftoi. 

But a TV power transformer could be used 
by placing the 6 and 5 V windings in series. 
The 5V winding is usually good only for a 
Little over 3A. By bringing out a separate 
lead for the 6L6 modulator filaments, 
however, the filament drain can be split 
into 3.5 and 1 A sources, as shown in Fig. 
14. If such an arrangement is not neces- 
sary, the two separate lines can be paral- 



Identify R132. Three leads are con- 
nected to one side. One goes to pin 7, 
VI 08. Remove and ground it. Remove the 
other two leads, solder and tape them 
together. Identify RI3L Place a jumper 
across it or remove it and tape the leads 
together. Identify and remove R133 and 
the lead going from it to pin 7, VI 05. 
Remove R129 and R130, taping up the 
remaining leads. 

Identify pin 7, VI 03. Remove both 
wires and solder and tape them together. 
Ground pin 7. Remove the lead from pin 7 




HIGH VOLTAGE 
* TO RECTIFIERS 



•» | IV, 3.5A 



12V, (A 



Fig. 14. 12V filament power supply. 



of VI 02. Run a 20-gage or 
the following chart: 



wire via 



FROM 


PI 


N TO 


PIN 


V104 


1 


V105 


7 


V105 


7 


VI 02 


2 


V102 


2 


R132 


tap 


VI 05 


7 


P103 1 




V107 


2 


P103 4 





The 1 2V (ac or dc) can now be fed into 
pins 2 and 4 of PI 03 with 3.5 and 1A 
sources. 

Front Panel Controls 

Remove the crystal compartment door 
and fit a new piece of aluminum for the 
front panel. This is best done by using four 
sheet-metal screws. Removal of the relay 
contact covers should provide sufficient 
clearance for jacks, switches, etc. Details of 



EXTENDED 
LEADS 




MIC VOL 

R-l« 

(R-Hl REMOVED) 



52 

CHANNEL 
SELECTOR 



A, 




Sto RELAY COILS 



TO P-*G2 



S3 



Al - A2 



PJN 2, P-103 



PIN 16 -• 

PIN II ** 



TVfi MIC INPUT 



RF 

SAMPLING -*■ 
CIRCUIT 



Du, 



X 



n 



MONITOR 



Fig. 1 5. Wiring of front panel controls. 



56 



73 MAGAZINE 



CUT TO a/ie 



fi^ 



«r 




OLD 
COUPLING 




3/4 in 



T 



■4-3/8 if* 



LOCATION OF CONTROL HOLE 



O 




1/4 m, BRASS OR 
STEEL ROD 



BUSHING 



\ 



V 

^- FRONT PANEL 



NEW BRACKET 





1/4 in 



NEW BRACKET 



Fig. 16. Mechanical details of manual peaking control 



the hookup are shown in Fig. 1 5. 

Microphone volume was originally con- 
trolled by an aneroid barometer attached- 
to a potentiometer. This is the large can or 
cylinder directly behind the crystal switch- 
ing relays and is marked R142 on the 
schematic. Remove and disassemble it, 
extending the connecting leads to the front 
panel. Extract the potentiometer and re- 
mount it on the front panel. 

To avoid making a number of con- 
nections to the front of PI 02, I decided to 
connect S2 through the relay rack com- 
partment directly to the coils. This involves 
removing the phenolic covers and cutting a 
small hole in the top cover to clear the 
leads. Removal of the back cover involves 
some unusual arrangements. There arc two 
wires going through it which must be 
unsoldered to effect its removal. Instead I 
extended the slit through which they ran 
to the bottom of the plate. This can be 
done with a hacksaw blade or small file. 
Wires were then soldered to the side of the 
relay coil not having a jumper to one of its 
own contacts. 



Power leads are attached in the same 
manner as to the receiver. The AI-A2 
switch allows the transmitter to be keyed 
A2 with its internal oscillator with the 
microphone PTT connection. For Al or 
A3 it is left in the A I position. 

Manual RF Peaking 

Unless a 2HV, 6A power supply is 
available, automatic tuning is not recom- 
mended. The supply shown in Fig, 6 is not 
capable of handling the load of the Inning 
motor, but will feed the keying and crystal 
switching relays nicely. Manual peaking of 
the rf stages requires relatively little con- 
version. 

Begin by locating motor BI01. It is 
mounted by six screws which attach 
through the main chassis to standoff posts. 
Remove all six screws and the motor- 
brake assembly. Cut and tape all three 
leads connected to it. Using a splined 
wrench remove the drive coupling from the 
end of the asssembly. Also remove the two 
center standoff posts and reinstall them on 
the chassis in their old location. Drill a hole 



MARCH 1972 



57 




Fig. j 7, Installation photo of manual tuning fea- 
ture, 

to accept an old potentiometer bushing as 
shown in Fig. 16. The l A in. shaft must be 
cut down to 3/16 in. on one end. If no 
other method is available, one can put the 
rod in the chuck of a V4 in. drill and hold a 
file against it until the proper diameter is 
reached. The method is crude, but works. 
Mount another bushing in the new bracket 
described in Fig. 16, Install the entire 
assembly as shown in Fig. 17. 

Locate K107. Remove the jumper going 
from the coil to one of its own contacts. 
This frees the PTT system to work without 
the tuning mechanism. 

In operation the transmitter is peaked 
up by observing the output. A relatively 
small excursion of the tuning knob covers 
the entire 2 meter band. 

Relative Output Indicator 

The output indicator is shown in Fig. 
18. The diode can be almost any rf type. 
Output is about 1 — 2 V. 



Figure 19 shows some of the connector 
layouts and a few miscellaneous dimen- 
sions which may be of help in the con- 
version of these units. All diagrams are 
front views. 

Many of these ARC-3 units have been 
sitting unused in warehouses for some 
time. Therefore components may have 

aged considerably and it may be necessary 
to repair the units before they are conver- 
ted. A borrowed 28V high-current supply 
can be used to operate the equipment in its 
original configuration long enough to as- 
sure proper operation. If problems are 
encountered, be suspicious of the capaci- 
tors, as they are wax units and often leak 
or short. This preliminary checkout is 
highly recommended, It can save many 
headaches later. 

RCVR FRONT PANEL- 1-3/4 in. X 7 in. 
XMTR FRONT PANEL- 5H/2 in. X 6-1/2 in, 





P-202 



P-IQ2 



(FRONT VIEWS OF ALL PLUGS) 





P-IOI 



P-IQ2 



Fig, 1 9, Connector pin diagrams. 



Afterthoughts 

The speaker in my receiver was mount- 
ed in the top of the cabinet over relay 
K201 and V207. It was necessary to 
remove these items to obtain clearance for 
the speaker and transformer. Others may 
wish to use another mounting location or 
speaker size. 



TO RF 
OUTOUT 



220K 




01 



22 K 



390 a 



ft? 



470 
pF 



*■ OUTPUT 



470 



r 



Fig. IS. Output indicator. 



The transmitter was originally set up to 
cover the entire 100 — 156 MHz band. By 
peaking the rf chain in the center of the 2 
meter band 5 considerably more output is 
available than for the wider band coverage. 
The tech manual gives complete informa- 
tion on the procedure, 

Thanks to Paul G. Branson, Richard 
Patisaul (WA4ARQ), and Thomas F. Evans 
for their assistance and encouragement in 
this work. 

- . .WA4NAI" 

1. Drawer 178P, Highway 301, Ellenton FL 33532 



58 



73 MAGAZINE 



Ed Baker WQEDO 
224 N. Buckeye 
tola KS 66749 



BLOWN FUSE 

INDICATORS 

For LOW VOLTAGE 



At first glance the unit to be described 
would appear to be strictly a luxury, but use 
it once, and you'll wonder how you ever got 
along without it. 

It is a well known fact that individually 
fused circuits not only give increased protec- 
tion to equipment, but simplify trouble- 
shooting by isolating the defective circuits. 
But it also means more fuses to check when 
troubleshooting. 

In ac equipment it is a simple matter to 
connect a neon bulb directly across each 
fuse; thus, when all is well all bulbs are out 
(being shorted by the fuse). When a fuse 
blows, the bulb is placed in series with the 
load and, glows (without allowing enough 
current flow to damage the defective cir- 
cuit). A look at Fig. 1 will make this 
operation clear, 

I "borrowed" the idea from a piece of 
military gear several years ago, and have used 
it ever since. Many hours have been saved by 
knowing exactly which unit to check when 
something "went south," 

Many times I have wished that such a 
system could be applied to the mobile rig, 
but since the 6V in my VW (or the 12 in 
your Cadillac) will not light a neon bulb it 
seemed out of the question. Then a light 
came on in the think department. How 
about incandescent bulbs? Theory could not 
find a flaw in the idea (at least not my 
limited theory) so it was decided to give it a 



1 10 VAC 



F 



LOAD 




LOAD 



FUSE GOOD 
NEON BULB OUT 



Fusf 6L0WN 
NEON BULB LIGHTS 



Fig. 1 



AMATEUR 

ELECTRONIC SUPPLY 

- JuM - 




9* Stocky* 




ROBOT MODEL 70 MONITOR 
ROBOT MODEL 80 CAMERA 

25mm, f 1.9 lens 

25mm, f 1.4 lens , 

25mm, f 1.4 Macro lens 



$495 
.$465 
■ $ 30 
.$ 40 
. $ 60 



AMATEUR ELECTRONIC SUPPLY 

4828 West Fond du Lac Ave. Milwaukee, Wis. 53216 

Phone (4/4) 442-4200 

HOURS: Mon & Fri 9-9; Tu«. Wed & Thurs 9-5:30; Sat 9-3 

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ALL Hail Orders and Inquiries should be sent to our Milwaukee stare. 



To: AMATEUR ELECTRONIC SUPPLY 

4828 W. Fond du Lac Ave. Milwaukee, Wis. 51216 
I am interested in the following new equipment; 

1 have the following to trade: (what's your deal?) 



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] Master Charge* ] Bank Amen card ] American Express 

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DATE 



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MARCH 1972 



n Send Robot literature 
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Tone Bum Encoders 



UP TO 5 FIXED 
TONES 

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ADJUSTABLE: 

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NO BATTERIES 

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TONE POSSIBLE 

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WARRANTY 




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Prices: MODEL TB-5 
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{18O0;l 950,2 100,2250, 
2400 Hz) 

(111* residents, 
add 5% tax) 



r Electronics 

Box 1201 B 
CHAMPAIGN, ILL. 
61820 



FM YOUR GONSET 
COMMUNICATOR 



Newt Plug- in modulator puts the 
Communicator transmitter on FM, 

No modification or rewiring of your 
Communicator. Just plug into mike 
jack and crystal socket. 

Compact self-contained modulator 
measures 4" x 3" x 1 Y*\ 

Works with Communicator l f II, III, and 
IV. 

FM at a tenth the cost of a new rig. 

Frequency adjust for netting built in. 

Built-in tone burst available. Keyed by 
push-to-talk switch. 

$34 50 postpaid U.S.A. Built-in tone 
burst $10.00. Specify Communicator 
model and tone-burst frequency. 5% 
tax in California. (HC-17/U crystal 
and 9 volt transistor battery not 
supplied.} 

Send for free descriptive brochure. 



1 




practical test, using a sealed beam unit from 
a headlight as a "load/* it worked! 

The values used were selected for easy 
calculation, but the theory will hold in any 






/£s 60 mo 



- BATTERY 



ILOAD 



X 




xv 



60 mo 
f DIAL 
LIGHT 



S VEHICLE 

BATTERY 



I 



LOAD 



FUSE GOOD 
DIAL LIGHT OUT 



FUSE BLOWN 
OIAL LIGHT GLOWS 



Fig. 2. 

case. Assume, for example, a 6 A load. The 
next higher rating of fuse is 10A, which 
should give adequate protection. Now, con- 
nect a 60 mA pilot lamp across the fuse. If 
all values are considered to be exact (of 
course they never are, but this is theory) our 
circuit may now conduct 10.06 A before the 
fuse blows. If a short develops at point A in 
Fig, 2, the fuse will blow, but the lamp will 
merely have its normal brilliance, announc- 
ing to one and all that Fl has blown. If the 
short is only momentary, the bulb will be 
placed in series with the load, but ap- 
plication of Ohm's law will show us that our 
6A load has a resistance of only l.Ofi, while 
the 60 mA bulb has a resistance of 10012, 
thus most of the applied voltage will be 
dropped across the bulb, and it will still 
light. 

This method worked out so well on the 
mobile rig that it was also applied to the 
entire automobile, with all the bulbs instal- 
led on a single panel just below the dash. 

Unless you have a large supply of pilot 
light sockets and jewels on hand, this would 
at first appear expensive, but there is a 
sneaky way around this. Bulbs mount nicely 
in a grommet set into a hole, and coating 
them with a special paint made for putting 
orange parking lights on older model cars 
makes a very attractive installation. In the 
event the bulbs tend to creep out of the 
grommets, a drop of Duco cement applied to 
the bulb and grommet will cure this, and 
replacement is so seldom that connection 
may be made by soldering directly to the 
bulbs. . . .W0EDO 



60 



73 MAGAZINE 



DYCOMM 10-0 FM BOOSTER 

10—15 watts drive produces 90—100 watts 
output. All solid state. Requires 13.5 VDC 
power, automatic Xmit— Rec. switching. Small 
5"x5"x8". Fantastic warranty. Get yours now 
for only . . . . $195.00 

P1416 — 15 amp ac supply for your 10-0 

$75.00 

DYCOMM "D"FM BOOSTER 

10-15 watts input - 40-55 watts out! 13.5 
VDC required — auto switching ready to 
go , $99.95 



DYCOMM "E" (not shown) 

Boost your 1—3.5 watt rig to 20- 
13.5 VDC at 3.5 amps 



30 watts out. 
$79-95 



Bid 



DYCOMM "ES" (not shown) 

Use your 1—3 watt rig & get 40—50 watts out 
13.5 VDC at 6,5 amps $99.95 



0** 



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PHONE 

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3850 SOUTH FREEWAY 
FORT WORTH, TEXAS 76110 



RADIO BOOKSHOP 



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Reprints from the FM Bulletin (Feb 67-Feb 68) 

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three oscillators for tuning up FM receivers, inex- 
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Chronicles of 76, a simple TVI eliminator, converting 
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THE BEST OF FM $4.95 

A huge selection of the best technical and con- 
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Listing, by state and city, of all repeaters, both 

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REPEATER BULLETIN $2.00 YR 

Monthly bulletin of news and activities of the New 
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living in the New England states who are active on 2m 
FM. Outside of this area the subscription price is $2 
per year. Issue number one was January 1972. 

The Bulletin is the place where the mass of FM 
information is published that doesn't make it into 73 
because there just isn't enough room- It runs about 24 
pages per month (8% x 11). 

If you are interested in a subscription send your 
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RTTY FUNDAMENTALS $150 

This book gives you all you need to know to get 
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108 QUESTIONS AND ANSWERS $1 .95 

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Take advantage of this and buy at the wholesale price. 
While they last only. 



62 



RADIO BOOKSHOP Peterborough, New Hampshire 03458 

Order on page 64. 



73 MAGAZINE 



RADIO BOOKSHOP 



TELEVISION INTERFERENCE 



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ask. Includes a lot you probably didn't even know yoq 
didn't know! Maybe a lot you don't even want to 
know. But it is all there - lengths of antennas and 
coax of different types for quarter, half and full wave 
feedlines and antennas for all amateur bands, coax 
connectors and how to use them, accessories, switches. 
What ham or even engineer can function without this 
reference data at hand? 

CONVERTING COMMERCIAL FM GEAR $2.96 

Particular emphasis on converting and using 
Motorola equipment for all of the VHF FM bands, 
including power supplies, antennas, and all of those 
details you need to know to buy and convert those 
commercial rigs and use them as repeaters or with 
repeaters. 

CALL LETTER DESK PLATE $1.95 

How about dressing up your operating table with a 

desk plate showing your first name and call? These 
embossed desk plates are nice - and inexpensive* No 
zero available, sorry. There is room for twenty letters 
and spaces total* 



VHF ANTENNA HANDBOOK $2.95 

If you are now or ever intend to be active on any 
of the VHF bands can you really afford not to spend a 
lousy $2.95 for a complete and detailed book on VHF 
antennas? You will find descriptions, dimensions, 
tuning data, and diagrams of all types of antennas in 
this book. From an instant coathanger antenna to a 
giant collinear beam, it is all here, Your antenna is the 
cheapest amplifier you can build. Get this book. 

$7.95 
RADIO HANDBOOK The book has been nationally 
advertised at $12.95, however we have a few copies 
available at this special price as a close-out on the 17th 
edition. 850 pages of handbook data and construction 
projects. This is one of the best book bargains you'll 
find -while it lasts! 

ATV ANTHOLOGY $2.95 

Invaluable book if you are interested in amatevr 

television. This book contains reprints of the most 
important material from the now defunct ATV 

Bulletin. 

73 BINDERS $4.95 

These are not available as a subscription bonus. But 

you still need them to make your issues of 73 stand up 
on the shelf. It also helps keep back issues from 
getting lost or spilt on. Or into the hands of the Jr Op. 
The binders are a gorgeous red and come with the 
nicest set of year stickers you've ever seen. Dress up 
your shack with these binders. 



FM REPEATER CIRCUITS MANUAL 
HADRBOUND EDITION 



$4.95 
$6.95 



DX HANDBOOK 



$2.95 



This 300-pIus page book has material on 
basic FM repeaters, national standards for FM re- 
peaters, carrier operated repeaters, tone decoders for 
repeaters, controlling repeaters with tones, improving 
repeater intelligibility, minimizing desensitization, 
solving intermodulation problems, digital identi- 
fication, the WB6BFM identifier, a computer- 
optimized digital identifier, WAOZHT design data, the 
Curtis identifier, the K6MVH auto patch, the Zero 
DKU autopatch, the touchtone autopatch, setting up a 
mobile station, encoders for sub-audible, tone burst 
and whistle-on use, multichannel scanning, RF pre- 
amplifiers for repeaters, antennas fox 2m FM, collinear 
gain antenna for repeaters, welding rod groundplane, 
high gain mobile antenna, poor man*s frequency 
meter, signal generator circuits, RF power measuring, 
adjusting deviation, pocket sized transmitter and 
receiver, low cost portable transmitter for repeater 
use, UHF transmitter, super-regen receiver, repeater 
zero beater, repeater controller, 10-minute timer, 
repeater audio mixer, and more! 



How to work*DX, how to get QSLs, country lists, 
award lists, postage lists, QSL bureaus, maps of the 
World, North America, Caribbean, South America, 
Africa, etc. Great circle maps centered on major U.S. 
cities, bearing charts for beam headings for major 
cities, how to go on your own DXpedition, and much, 
much more, This is the biggest selling DX Handbook 
ever published, written by 73's editor-publisher who 
has DXed from nearly 100 countries. This book 
includes a wall sized DX map of the world, itself 
worth the price of the book. 



U.S- MAPS 



Four for $1.00 



These wall sized maps show the states and call 
areas. They are specially designed for coloring to show 
the progress toward the Worked All States award of 
ARRL or the Worked Almost All States award put out 
by 73 (for proof of contact with 49 states). Since you 
will probably be wanting to work for the award on 
several bands you will want several maps. They come 
in groups of four* 



MARCH 1972 



RADIO BOOKSHOP Peterborough, New Hampshire 03458. 

Order on page 64. 



63 



^™ 



RADIO BOOKSHOP 



BACK ISSUES OF 73 - VOL. I $3.95 

This is an assortment of twelve different back 
issues of 73 from the years 1960 through 1964. 
Normally these back issues would cost you $1.00 or 
more each, but since this assortment is our choice 
instead of yours, thus the bargain. Here is a good way 
to build up youi technical library with hundreds of 
interesting and valuable technical articles and con- 
struction projects. You may have missed these great 
issues when they originally came out, but don't miss 
the fun of reading them now! The emphasis on articles 
with no operating news or monthly columns means 
that little of the material is dated. 

BACK ISSUES OF 73 - VOL. II $3.95 

Twelve different back issues of 73 from the years 

1965 through 1967. These are the real vintage years of 
73 for home builders of transistorized gear. Lots of 
VHF projects and gadgets galore. See for yourself 
what 73 was doing back when QST was still bringing 
you only tubes. At this price you get our choice of 
back issues. This is an excellent way to fill in missing 
back issues, if you like to gamble, 

BACK ISSUES OF 73 - VOL. Ill $3.95 

Twelve different back issues of 73 from the years 

1968 through 1970. These bundles are already made 
up so you have to accept our choice at this price. 
Individual issues for most months are still available for 
$1,00 each for these years. 

BUMPER STICKERS Four for $1 .00 

Stick these bright stickers on your car bumper or 

window to let passing FMers know what channel you 
are monitoring. Available in any combination of the 
following channels: 70, 73, 76, 82, 85, 88, 91 and 94, 

WORLD DX MAP $1.00 

This is the same wall-sized DX map that is included 
with the DX Handbook except it comes to you rolled 
up instead of folded. This is so you can put it on the 

wall or have it framed. The map is designed with all 
country prefixes indicated and space for you to color 
in the countries as you work them. Visitors can see 
immediately how much of the world you have 
contacted! The zones are on the map as well as 
prefixes. Maybe you need several maps. 



CUSTOMIZED DX BEARING CHART 



$4.00 



This is not available on the subscription bonus 
because it is provided purely as a service of 73, An 
amateur who works for a big computer company has a 
program which permits him to plug in your locution 
and have it print out the bearings of all of the 
countries of the world from your shack. Once you 
have this list you will use it for every DX contact. The 
chart gives the bearing and distance to all major cities 
and countries. Be patient when you order for these 
have to be run through in groups at this low cost to 
you. 



TRANSISTOR PROJECTS $2.95 

Crammed with home construction projects such as 
a complete communications receiver, a converter 
converter, CW filter and monitor, 10-1 5 -20m FET 
converter, 40 & 160m converter, 2-6-1 0m converter, 
30 MHz i-f strip, audio bandpass filter, 6m FETs, 
audio derived AGC, 432 MHz converter, 2m converter, 
megaphone, 1296 MHz converter, simple 10m 
receiver, FET preamps for 144 & 432 MHz, noise 
clipper, SSB transmitter, 6m station, 6m ultra-midget, 
160m transmitter, 432 MHz exciter, varactor tripler 
for 1296 MHz, FET VFO for 80m, VFO for HF and 
VHF, VHF parametric amplifiers, diode controlled 
break-in, slide bias modulator, modulating transistor 
transmitters, FET audio compressor - plus technical 
and theory material on designing RF power amplifiers, 
zener diodes, integrated circuits, simplified transistor 
design for the amateur, CW monitor, RTTY indicator, 
crystal oscillators and more. 

FM REPEATER HANDBOOK $6.95 

This hardbound book from Howard Sams is not 

available on the subscription bonus deal. Sorry, 
because it is one you will want if you intend to set up 
a repeater. 

SIDEBAND LOG BOOKS $2.00 

Are you tired of using a log book designed back in 
the 1920 ? s? Try one of these 1972-type logs designed 
by W2NSD/1. A pad of 125 log sheets, SVixlt, with 
20 contacts per page will last you for 2500 contacts- 
Try this first really modern log sheet. 

DIODE CIRCUITS HANDBOOK $.95 

There are 115 diode circuits in the handbook, 

including power supply applications, regulators, ac 

meter applications, all sorts of receiver detectors 

(AM-FM-SSB), noise limiters, squelch, AGC, varicap 

tuning, audio clippers, compressors, FM modulators, 

RTTY keying, varactor multipliers, field strength 

meters, wavemeters, noise generators, and many etc. 

Very enjoyable book. Cheap too. 



i — 

| Mail to 



Name. 



RADIO BOOKSHOP 

Peterborough NH 03458 



1 



Street, 



m City. 



i 



State 



Zip 



Call 



Please enclose separate sheet listing books ordered. 



°-i 



64 



73 MAGAZINE 



Hank Olson W6GXN 

P.O. Box 339 

Menlo Park CA 94025 



Addendum To The 



W1PLJ Counter 



One of the best amateur radio-oriented 
frequency-counter articles, in my 
opinion, was published in 73 magazine in 
February 1968 by WIPLJ. 

Although the WIPLJ counter was de- 
signed around RTL logic, considered to be 
obsolete for new designs by many engineers, 
it still has much to recommend it in terms of 
price and performance. RTL is a logic form 
that was first to be I C-im piemen ted and so 
has a few features upon which the newer IC 
logic families have improved. RTL is, how- 
ever, still probably the most durable IC logic 
form in the hands of the beginner. Mistakes 
in wiring or inadvertent shorting of leads 
together in testing are usually forgiven by 




Fig t 1. DCU board layout Boards will be made 
available by Stafford Electronics Inc T , 427 S. 
Benbow Rd, Greensboro NC 27401. 



RTL, Also, since most hams are used to 
devices being turned "on" by a voltage 
input, RTL is easier to understand than the 
more sophisticated "current sinking" logic 
forms (DTL or TTL). 

The original counter article was written in 

■ 

such a way as to allow the builder to choose 
from a number of ICs (Fairchild or Moto- 
rola), and so IC pin numbers were not given. 
As such, the article was not really a con- 
struction article, 

I began construction of the WIPLJ coun- 
ter by the hand-wired method used in the 
original article. After making two of the 

(10) HE-2 LAMPS 



®©©@©©©©©<3) 



(K» 220K I" 

RESISTORS 



+ I50V- 



10 X 
RESISTORS- 




GATE 
0*r DCU 
ONLY) 



Fig. % Parts layout of DCU, 



MARCH 1972 



65 



^™ 



■■■ 




TELEVISION INTERFERENCE 

CAN BE CURED 

Is there a radio operator anywhere 
who has not had trouble with 
television interference? Unlikely! 

NEW, 

UP TO DATE... 

only $1.50 




fUBUCATIJ 



Television Interference Handbook 

Send to: 

73 Magazine, Peterborough NH 03458 



Name 
Street 



City 



State 



ZIP 



Decade Counting Units (DCUs), the task 
seemed to have no end in sight. This much 
of the counter was a "shot in the arm," 
however, as I could hook the DCUs up to 
+3.6V, +1 50V, and a pulse generator, and 
watch them "count" and display. In order to 
simplify the repetitive job of constructing 
DCUs, a PC board was taped up, as shown in 
Figs. 1 and 2. This board makes building the 
counter much easier, combined with another 
simplification. The neon indicator systems 
were pulled off old Hewlett Packard AC4A 
tube type DCUs (the ones that had four 
12AU7s in them). These are often available 
in surplus stores, and really speed up the 
mechanical implementation of the display, 
since the numbers and so forth are all there. 
Similar DCUs that are suitable were made by 
Berkeley and Detectron, but the H.P. units 
were the easiest to use in my opinion. I 
personally wouldn't pay much over $3 for 
an old AC4A (without tubes) since the price 
of ten NE2s is only about $1 and that of the 
least expensive "nixie" (Burroughs B5750) is 
only $6.75. 

The particular transistors used on my 
DCU boards were 2N720As which I hap- 
pened to find a "good deal" on, but the 
2N 1893s or 2N3877s recommended by 
W1PLJ wUl also fit the board. The ICs 
chosen for the PC board do cause some 
restriction, but those specified are the least 
expensive choice for eight RTL inverters in 
two IC packages, and two dual JK flip-flops. 
(The Motorola HEP parts will be somewhat 



+ I5V 




OUT 



S G 



C2-S0 TO 400 pF (MILLER J6QBJ 
01 -2N3646* 2N708 ar HEP 50 
Q2-HEP Q02 r MPF 102 (MOTOROLA) 



o o o 



Q2 



BOTTOM VfEW 



Fig, 4 A. 200 kHz crystal standard for counter time 
base. 



66 



73 MAGAZINE 



+ 3.6V 



TO x 

ZOO KHt-*— ) 
BUFFER ' 



INT EXT EXT 
°"~©KHz 




JjpO+wv 



CI - WIRE "GIMMICK" IC3 TO IC7-MC 780P (MOTOROLA) 

ICI-^L 923 or HEP 383 QI-2N3646, 2N706 or HEP 50 

ICZ-pL 900 or MC OOOG (MOTOROLA) 

Fig, 3, Divider section. 

more expensive than the Fairchild juA and 
Motorola MC numbers they replace, but the 
HEP parts are more generally available.) 

The other simplifying modification of the 
counter was the use of MC780P decade 
counter ICs. These ICs were unavailable 
when W1PLJ wrote the original article. They 
make the frequency standard divider section 
much easier to wire and eliminate any 
divider adjustments. The MC780P costs 
about five cents more than two MC790Ps, 
which were used as the two lowest fre- 
quency decades in the original counter, but 
are well worth it in simplification. The new 
divider section is then as shown in Fig. 3. 



#-Q+l5V 





COM 



CI-.OI pF, tKV DISK 
C2-S0 pF, 25V 
C3- 01 mF 
C4-I0O oF 
C5-ljiF 



RIH50K 

R2-(0jv 

R3-6.8K 

R4-IK (VOLTAGE ADJ) 

R5-IK 



ft 

117 VAC 

TO + 3,5V AND +I50V 
SUPPLY XFMR 



01, D2-IN4002, HEP 136 (MOTOROLA} 
iCI-LM 305, LM 300 (NAT. SEMICONDUCTOR) 
CA 3055 (RCA) 

LM 305H (ADVANCED MICRO-DEVICES) 
SG 305T (SILICON GENERAL) 
Tl- TRIAD F40X Fl^3A, 3 AG 

D5J-NE5I 



Fig. 4B. Regulated power supply for 200 kHz 
crystal standard. 



you/ 






ASKED/. 
FOR 




HERE IT IS! . . . one complete U.S. Callbook 
and one complete DX Callbook per year and no 
change in price. In addition you can keep your CALL- 
BOOKS up-to-date through a subscription to the new 
Service Edition Series published each March 1, 
June 1 and September 1 — each one covering new 
licenses and all activity during the preceding quar- 
ter. Annual subscription to complete Winter CALL- 
BOOKS plus 3 Service Editions only $14.95 postpaid 
'for the U.S. and $11.45 postpaid for the DX. 



Over 285,000 QTHs 
in the U.S. edition 




Over 180,000 OTHs 
in the DX edition 



These valuable EXTRA features included in both editions! 



QSL Managers Around 
the World! 

Census of Radio 
Amateurs throughout 
the world! 

Radio Amateurs' License 
Class! 

World Prefix Map! 
International Radio 
Amateur Prefixes 



Prefixes by Countries! 

Zips on all OTHs! 

A.R.R.L Phonetic 
Alphabet! 

Where To Buy! 

Great Circle Bearings! 

International Postal 
Information! 

Plus much more! 



See your favorite dealer or order direct (add 250 for 
mailing in U.S., Possessions & Canada. Elsewhere add 

500). 

50 YEARS OF SERVICE 
TO RADIO AMATEURS 

GET YOUR NEW ISSUE NOW! 



WRITE FOR 

fru 

BROCMRf! 



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ca 



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M Lake Bluff. 111. 60044 



MARCH 1972 



67 




IC-21 $389.00 Net 

This is an entirely new approach in 
2 meter FM gear. Just imagine 24 
channel capability, SWR meter and 
S meter, plus netting condenser on 
each transmit and transceive crys- 
tal, plus many other features origin- 
al with this unit. 

Send your order today 




Incorporated 



A u / li oris e d I) is t rib u tor for 
Indue Products 

185 West Main Street 
Amsterdam New York 12010 




AVAILABLE FOR THE FOLLOWING 
2 METER TRANSCEIVERS 



Drake 
Regency 
Standard 
Swan 

Varitronics 
Unimetrics 



ML, TR-22 | 

HR-2 

SRC 826 

FM2X 

FDFM-2,FDFM-2S,IC2F 

Mini Vox III 




WRITE FOR NAME OF NEAREST DEALER 




CRYSTALS 

the "long playing" crystals 

BOMAR CRYSTAL COMPANY 

201 Blackford Ave., Middlesex* H J. 08846 
Phone (201) 356-7787 




Completed counter. 



The original counter article did not show 
a power supply for the crystal standard, and 
so a new crystal oscillator and regulated 
supply for it was designed to fit my particu- 
lar needs. The use of the LM305 IC-regulator 
very simply accomplishes the job of obtain- 
ing a small amount of regulated +15V 
needed for the crystal oscillator and buffer. 
Note that a 200 kHz surplus FT241 crystal 
was used in this version of the counter. 

While it may be argued that the 1 MHz 
crystals (being AT cut) are more stable than 
the crystal used here, the 200 kHz FT241 is 
quite adequate for" the four-place accuracy 
of this counter. These 200 kHz crystals are 
available from JAN crystals for SL75 plus 
104 postage (Jan Crystals, 2400 Crystal 
Drive. Ft. Myers FL 33901). 

The finished counter as packaged is 
shown in the photograph. This counter has 
been immensely helpful in routine lab work 
for setting oscillators to frequency quickly y 
and many other tasks. The main advantage 
of a counter is not its great accuracy, but 
rather its great speed of reading out frequen- 
cy. Since the counter does all the work, for 
instance, you can connect it to an oscillator 
that you are slowly heat-cycling and look up 
only occasionally to log the temperature and 
frequency. In short, it is a gadget every 
experimenter ought to have. 

. . .W6GXN 



68 



73 MAGAZINE 



Ken W. Sessions, Jr. K6MVH 



Constant - Currant 
for Ni-Cads 




. . . Lets you charge your batteries the way the 
manufacturer would want you to. 



If you own a hand-held transceiver with a 
nickel-cadmium battery pack but you 
don*t have a charger, youVe probably been 
going about the recharging task the hard 
way — connecting a low-voltage dc source to 
the battery, monitoring the current drain 
with a miliiammeter, and using a pot to 
increase the applied current to the required 
rate as the battery gradually becomes 
charged, That's an effective system, of 
course, but it requires one heck of a lot of 
attention if you want the battery up to snuff 
at the end of the period. 

As the battery regains its state of charge, 
it will tend to draw less and less current, 
always seeking a state of balance between 
the applied voltage and the battery poten- 
tial. When you charge the hard way (as most 
of us HT owners have), it's very hard to keep 
track of the time on charge at the right rate, 
which does make it extremely easy to end 
up overcharging — and destroying some of 
the cells in the battery. 

Since ni-cads should be charged for 
15 — 16 hours at 10% of their milliampere- 
hour rating, the monitoring and adjustment 
process can keep you hopping and be a real 
drag, The obvious solution is to attack the 
problem the way Motorola does with its 
factory-made charging systems — that is, to 
use a charger whose output current remains 
constant over the full 16-hour charging 
period. 

Building such a charger is an incredibly 
simple job. All you need are transformer, 



small lamp, resistor, and a diode. Since the 
resistor— lamp combination (and the battery 
under charge, of course) will determine the 
current drain, the pair should be selected 
according to the requirements of your parti- 
cular battery. 

A 28V transformer is right for virtually all 
Motorola ni-cads, which are themselves typi- 
cally just over half this value. In most cases 
(where the battery has a capacity of a 
quarter of a milliampere-hour or more), the 
lamp itself should be a 28V type. The 
charger circuit is shown in Fig. 1 . 

The resistor should be selected to draw 
25—30% of the current drawn by the lamp. 
You can determine the values experimen- 
tally if you have a junkbox that is fairly rich 
in lamps and resistors. Place a miliiammeter 
across the charging contacts (when the bat- 
tery is NOT in the circuit) and measure the 
dead-short current. It should be exactly 
twice the value of your battery's 16-hour 




CHARGE 
CONTACTS 



# SEE TABLE I FOR VALUES 



Fig. i. Constant-current charger circuit for 15V 
ni-cad batteries. Caution: Don't try to charge 
mercury batteries with this charger or you'll have 
battery all over the walls of your shack! 



MARCH 1972 



69 



REPEATER 

CIRCUITS 

MANUAL 



If you're into FM, you'll want to have 
this incredibly complete manual of FM 
circuits. You don't have your own repeat- 
er yet? Well, you've been thinking of 
it . . . admit it- Some fellows even have 
gone so far as to have a repeater in their 
car so they can extend the range of their 
hand units! 

This book, over 300 pages long, has 
|ust about every circuit that you could 
possibly want Many of these have been 
published elsewhere, but many haven't, 
too. And you can go out of your mind 
trying to find a circuit when you want 
it. . . so here they are, all in one handy 
place! 




ONLY 





ppd 



73 Magazine 
Name 



Peterborough NH 03458 



Cdll 



Address, 



City- 



State- 



-Zip, 



$6.95 hardbound, $4.95 softbound enclosed 
for FM Repeater Circuits Manual. 



Table I. Lamp and Resistor Values for Popular 

Motorola Units 



Radio 


16~hr 
Batt Rating Charge Rate 


Resistor 


Lamp 
Current 


HT-200 
HT-220 
HT-220 
OMNI 


500 mA-hr 
235 mA-hr 
450 mA-hr 


50 mA 

25 mA* 
45 mA 


12012 
270ft 

180ft 


70 mA 
40 m A 
70 mA 


HT-100 


70 mA-hr 


7 mA 


100K 


#♦ 






•Charge for 15 hours at specified rate. 
**Use a GE type B2A neon glow lamp- 
charge rate. The approximate values for 
resistors and lamps suitable for use in char- 
gers for most popular Motorola HTs are 
shown in Table L If you use these values, be 
sure to double check the short-circuit cur- 
rent as indicated above before connecting 
the battery. It's possible you'll have to make 
some slight modifications in the resistor 
values, since those shown were derived by 
calculation rather than by an empirical 
process of in-circuit measurement. 

When the battery is placed in the circuit 
(in series with the lamp), the voltage across 
the lamp drops to approximately half its 
shorted value, which will also halve the 
current; thus, if the short-circuit current 
measures 100 mA, the current will be 50 mA 
when a 15V battery is connected. 

Now that you've got the problem of 
building the charging circuit licked, you'll 
have to use some real ingenuity to get the 
battery charged. The mechanical problems 
associated with charging Motorola batteries 
are mind-boggling. There's just no simple 
way to connect test leads to the batteries. 
Motorola chargers are form-fitted to the 
battery so that when the battery is placed in 
the "pocket," a set of contact pins on the 
bottom of the charger connect with the 
battery at the right spot. But if you don't 
have a form-fitting battery holder, you'll just 
have to be clever about it. I made up a little 
wooden box into which the battery fits 
rather nicely, and installed a couple of 
screws at the bottom for contact pins. But it 
would have been easier to simply buy a new 
Motorola charger. If you have any ideas, I'm 
sure the rest of 73's readers would like to 
hear about it. 

. . .K6MVH 



70 



73 MAGAZINE 



The 
The 




Meter FM Rig 



Praise 




6LAbHAT\6 25 




6 CHANNELS/2 METER/TRANSCEI VER/25 WATTS 

Power is the keyword when discussing Gladding 25™, 
the two meter transceiver the experts recommend. 

Gladding 25 is so similar to our marine gear (we're the 
leader in AM and FM marine communications) we are able 
to take advantage of the tremendous buying power and pro- 
duction efficiencies our huge volume gives us. The result is 
remarkably low priced, A Gladding 25™ has the power, price 
and the features amateurs want most, with unmatched quality. 



• 25 Watts output * 0.3 micro volt uv sensitivity for 12 db 
SINAD • Dynamic microphone for unmatched audio • Six 
separately switchable transmit and receive channels • Crystal 
supplied for 149.94 simplex and repeater capability on 
146.34/146.76 and 147.34/146.94 mHz • 12 volt mobile unit 
has matching accessary AC power supply • Vacuum tube 
driver and final for reliability and economy • 8 pole crystal 
lattice filter • Solid state receiver • Transistor sockets • Glass 
epoxy printed circuit boards • Quick disconnect power plugs 

• Mobile mounting brackets • One watt output capabi 
for short range communications. 

Write for complete information. 



$04995 



for mobile unit 



$29995 

with accessory AC 
power supply 






-SIMPSON 

DIVISION OF ClAhbUMi CORPORATION 

P.O. Box 800, Biscayne Annex, Miami, Florida 33152 





DEVICES 



HAL DEVICES 

MODEL 1 550 

ELECTRONIC KEYER 



All the features of previous HAL keyers and more, 

TTL circuitry. Optional identifier for sending call 
letters DX and RTTY ops. take notice. Transis- 
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Rugged crackle cabinet with brushed aluminum 
panel. Designed for ease of operation. Model 
1550 only $64.95, With ID $89.95. 




HAL MAINLINE ST-6 RTTY TU 
Complete parts kit for the W6FFC ST-6 now in- 
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cuit boards (dnlled GfO glass) for all features 
Plug-in 1C sockets. Custom transformer by 
Thordarson for both supplies, 115/230V. 
506GHz. $135.00 kit. Screened table or rack 
cabinet $26 00 Boards and manual $16 50 
Shipping extra Wired units available. 

HAL TOUCHCODER II KIT $55.00 

Complete parts kit. excluding keyboard, for the 
W4UX CW code-typer All circuitry on one 3 x 6" 
G10 glass PC board. Plug-in IC sockets Optional 
contest ID available, $35 00 Watch for an- 
nouncement of the new HAL code-typers. both 
Morse and RTTY. 

HAL ARRL FM TRANSMITTER KIT 

Drilled, plated, glass epoxy HAL PC boards, 
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meter only $50 00 + shipping Cabinet and 
crystals excluded. Board only $7 50. 

DTHER HAL PRODUCTS 

ID*1 REPEATER IDENTIFIER . , $75.00 wired 

W3EFG SSTV CONVERTER 55 00 kit 

DOUBLE BALANCED MODULATOR- . 6.50 kit 

DIP IC BREADBOABD CARD 5 50 

MAINLINE ST-5 TU KIT , $50.00 

MAINLINE AK-1 AFSK KIT ... 27 50 

HAL RT-1 TU/AFSK KIT 51 50 




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ORDERING INFORMATION 

Catalog, including photos, of all items 24t post- 
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larger kits. Shipping via UPS when possible Give 
a street address 

HAL DEVICES, Box 365H, Urbana, II 6180T 

Phone 217 359-7373 



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Phone 217-359-7373 



Clifford Klinert WB6BIH 
520 Division Street 
National City, CA 92050 



The ESM/1 Transceiever 



The ESM/1 emergency signaling device is 
a self-contained pocket-portable unit that 
has a range of up to ten miles in fair weather 
daytime conditions. The device is solar 
powered and operates in the noncoherent 
light band. The emission is of the CW mode. 
Its dimensions are four by five inches, and 
about a quarter inch thick. Obviously it is 
solid state, very solid, with no moving parts 
of any kind. It must be very state-of-the-art 
you say? No indeed, this device appears to 
be at least twenty years old, and is probably 
World War Two surplus. So what is the 
trick? It's very simple; it's all done with 
mirrors. But this is a very special mirror, so 
let's take a look at how this device works 
and how we can put it to work for us. 

Theory 

At some time or another everyone has 
probably reflected the light of the sun with a 
small mirror. However one problem develops 
if the light is to be directed to a spot a great 
distance away, Because of the inverse square 
law and a few other things, the spot of light 
in the distance usually becomes invisible to 
the operator and the means of aiming it are 
lost. The following discussion will explain 
what has been done to provide a simple and 
effective means of aiming the spot of light at 
distances of several miles. 

It's easier to show than tell, so take a 
look at Fig, 1. Here we have two intersecting 
straight lines. The thing to notice is that the 
two opposite angles marked A and B are 
identical This comes from a theorem in 





Fig, 1. Equal Opposite Angles, 
angle A is the same as angle B. 



Note that 



geometry, but can be seen by inspection. 
For those who are interested in this, a high 
school geometry text should clear this up. 

The mirror consists of a sheet of glass 
with a reflective surface on one side that 
reflects from both front and back. This thin 
reflecting surface has a cross shaped opening 
in it that allows light to pass through the 
center, 

With these facts established, it is possible 
to explain the operation of the mirror in Fig. 
2. Starting at the light source (the sun), the 
light travels both the dotted and dashed line 
to the mirror. At the surface of the mirror, 
most of the light is reflected to the object of 
interest. However* because of the small 
opening in the surface, some of the light also 
travels the dotted line through the mirror 
and strikes another surface (not a mirror). 
The light is reflected from this surface in the 
solid line back to the mirror, much weaker 
in intensity because of the nature of the 
surface. Since the back of the mirror is also a 
silvered surface, the solid line is reflected on 
to the eye where it is seen as the image of a 
cross as projected on the surface. In the final 
leg of the light's travel, we focus our interest 
on the object. The light that makes up the 
image of the object travels the solid line to 
the eye. Since there is an opening in the 
mirror, the object is seen as it would 
normally appear, but through the hole in the 
mirror. It is in this configuration that proper 
aiming is achieved. If this explanation is not 
clear, the next section should clear it up. 

Operation 

At first glance, the instructions on the 



MARCH 1972 



73 



M 



LIGHT SOURCE 



EYE 

SURFACE 
(HAND) 




(RESCUE COPTER) 



Fig. 2. Mirror Aiming Diagram. The eye sees the image of the hole of the 
mirror on the hand, the hole in the mirror, and the object, all superimposed 
on each other. 



mirror are not very clear, so some instruc- 
tion is in order. The first step is to hold the 
mirror in the sun so that the cross shaped 
image appears on some surface, usually your 
hand. Now move your eye around so that 
the image on your hand is visible in the 
mirror. Your eye should be about two or 
three inches from the mirror. As soon as the 
cross is located, line it up with the cross 
shaped hole in the center of the mirror. 
What you see in the distance through the 
hole in the mirror is where the light is aimed. 
It is simply a process of lining up the three 
things; the image of the cross, the cross 
shaped hole, and the object. Keying can be 



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CRYSTALS FOR FWI RIGS 

Regency, Varitronies, Drake, Tempo, Swan, Stan- 
dard, etc, Receive $4.50 Transmit $5.50. Also 
crystals for police receivers — Regency, Bearcat, 
etc . $4.50 

Quick Delivery —Postpaid (3rd Class) 

DERRICK ELECTRONICS, INC. 

P.O. Box 457B, Broken Arrow, Okla. 74012 



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done by using slow or fast passes over the 
object to form dashes or dots, respectively, 
A little practice is required here. 

The uses of this device are obvious 
wherever a highly portable temporary means 
of communication is required - so long as 
the sun shines. Microwave or laser paths can 
be checked for line of sight clearance by this 
simple method before actual installation of 
equipment. Since no license is required, 
anyone can use it. And, if someday you find 
yourself sitting in one of those little rubber 
boats with nothing but ocean all around, this 
mirror may save your life! 

. . . WB6BIH 



AN/URR-13A receiver, tunes 220-450 MHi f 

1 15VAC $95.00 

LM-21 with calibration book, power supply and 

one cable $90.00 

TCS-12 or TCS-13 receiver & transmitter, tunes 

1 .5-1 2 MHz $125.00 

TN-233/SRC antenna tuner $5.00 

All available after May 1, 1 972 F.O.B. 

Hard wick, Mass. 

Order from: 

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2 METER PREAMP 

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20 db gain 

Noise Figure 2.5 

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Box 1245 'Springfield, Va. 22151 

73 MAGAZINE 



John Kennerdell WA8ZEL 
3000 S.O.M. Center Road 
Pepper Pike OH 44124 



LOW COST TRANSISTOR RF 



Semiconductor progress in the past few 
years has been nothing short of amazing. 
The transistor has evolved from the 20 
milliwatt wonder to a replacement for the 
6146. Although basically aimed toward in- 
dustry, this rapidly advancing technology 
can be of use to the amateur. One particular 
field of interest to the ham is that of rf 
power, where often today the transistor 
proves more economical and practical than 
the tube. Through proper transistor selection 
and well-designed circuits, the transistor 
must no longer take a back seat to the tube 
for economy, 

Transistor Selection 

The many merits of the transistor over 
the tube are well known to every amateur 
who took part in the great transistor vs. tube 
disputes a few years ago. But economy was 
seldom added to the list; "bargain" tubes 
and cannibalized television sets gave the tube 
man the edge. The story has changed, 
though, and today rf transistor list prices 
look a little more appealing. In the $5 and 
under price range a number of good rf 
transistors are presently available, as shown 
in the chart in Table 1 . This cross-section of 
popular types cannot only give you an idea 
of how much performance to expect for a 
given amount of money, but it can help with 
the selection of a type for any desired 
application, 

Two electrical specifications are given on 
the chart. Both are useful in the selection of 
transistors, yet often misunderstood. Pt, as 
might be expected, refers to power. Tech- 
nically it stands for "the total nonreactive dc 
power input to all terminals**, From this 



definition it would seem that Pt is the total 
dc input, and therefore the maximum power 
input of the transistor. Not so, however, for 
transistor technology defines power output 
as negative power input. In other words, the 
Pt rating refers to the amount of dc power 
input minus the output power. This cor- 
responds to the plate dissipation of a tube, 
for it is a rating of the amount of power that 
can be safely radiated as heat, expressed in 
watts. 

The second rating on the chart, the Ft, 
concerns the frequency limit of the tran- 
sistor, "The frequency at which the small- 
signal foward current transfer ratio extra- 
polates to unity*', the manuals claim. Trans- 
lated, that's the frequency at which no gain 
can be realized from the transistor. Of 
course, we are concerned with frequencies 
well below this rating, for in the interests of 
economy a transistor rf stage should have 
reasonable gain, hopefully at least 8 or 9 db. 
Exactly how far below this frequency the 
transistor will operate at a moderate ef- 
ficiency is often difficult to judge. 

This "highest practical frequency" de- 
pends mainly upon the percentage of ef- 
ficiency wanted. The 2N2102, for example, 
has an Ft of 120 MHz, but 50% efficiency 
cannot be obtained in operation above 10 
MHz. Output is possible above 10 MHz, but 
the low efficiency involved makes it imprac- 
tical from the technical standpoint. At the 
same time, other transistor types with simi- 
lar Ffs can operate well above 10 MHz with 
50% efficiency- For most HF types a figure 
of ten percent of the Ft gives a rough 
estimate of operating frequency. Further 
specifications of the types listed on the 



MARCH 1972 



75 



M 



chart, often including practical frequency 
limits, can be found in manufacturers' guides 
and manuals* More on obtaining these later. 

Assuming that a transistor running class C 
well below its Ft has a 50% efficiency 
(which, in most cases, is true), it is obvious 
that the dc power input of the transistor can 
safely exceed the PL In fact, at 50% ef- 
ficiency, the dc input can be as much as 
twice the rated Pt This should be apparent, 
for if half (507*) of the input is "lost" as 
output, the remaining half can be safely 
dissipated. 

There is one major disadvantage to in- 
creasing a transistor's dc input beyond the 
rated Pt* If, for some reason, the antenna or 
load shorts or opens, destruction of the 
transistor is likely. Having a power input 
above the Pt and no means of power output, 
secondary breakdown would take place in 
the transistor, and failure would be immedi- 
ate. For the sake of safety most transistor 
circuits are designed to have the dc power 
input not exceeding the Pt rating of the 
transistor. For then, even if the load is 
interrupted or shorted, the transistor will 



still be capable of dissipating the entire 
input. 

Another caution concerning maximum 
power input considers the effect of heat on 
the transistor. Most Pt ratings are rated at a 
case temperature of 25 C, or about 77 F, 
Higher temperatures rapidly reduce the ef- 
fective Pt. At 30° C, or about 86° F, some 
types lose as much as 75% of their rated Pt. 
Although room (ambient) temperatures 
usually won't be this high, the heat gener- 
ated by the transistor itself can easily raise 
the case temperature above 35 C As the 
temperature rises the transistor becomes 
incapable of dissipating the unused input, 
and thermal runaway takes place. 

Destruction of the transistor by thermal 
runaway can be prevented by the heat sink, 
With an effective surface area much greater 
than the transistor's case, the heat sink can 
radiate enough heat to maintain a safe case 
temperature. It is important to remember 
that the heat sink is not meant to increase 
the Pt above its rated value, but only to 
allow the transistor to dissipate heat and still 
be capable of its full Pt. 



Manufacturers: 






If more than one manufacturer is shown. 


MOT: Motorola 




price indicated is the lowest, and manu- 


GE: General Electric 




facturers are listed in order of increasing 


Tl: Texas Instruments 




price, 




Pt 


Ft 






Type 


W 


MHz 


Mfg. 


Remarks, Features, Similar Types 


2IM706 


1 


200 


MOT. GE, Tl 


Very popular HF/VHF osc. and low power amp, TO- 18 










case. Similar: 2N706A, 2N706B, 2N708 


TIS44 


1 


200 


Tl 


New "Economy Model/' plastic case. Similar to 2N706 


TIS48 


1.2 


500 


Tl 


"Economy Model/' plastic case. Excellent for VHF, 
Similar: T1S45, TIS46, TIS47, TIS49, TIS51, TIS52 


2N697 


2 


100 


MOT.TI, RCA, GE 


One of the earlier rf transistors. Slightly outdated for 










rf use, but still useful and inexpensive. 


2N1491 


3 


380 


RCA 


HF/VHF amp. Similar, more power and cost: 2NI492, 
2N 1 493 


2N2218 


3 


250 


TI.MOT, GE 


Similar, same price: 2N2218A, 2N2219, 2N2219A 


2N3118 


4 


250 


RCA 


1 W out on 50 MHz. 


2N2102 


5 


120 


RCA 


HF osc* and amp. Good performance to 10 MHz. 
High voltage (Vcbo=120V) and tolerant of current 
surges. Economy version: 2N2270 


2N3053 


5 


100 


RCA, MOT 


Low cost HF to 10 MHz. Similar: 2IM2405 


2N3866 


5 


800 


RCA, MOT 


One of the best values available for VHF/UHF osc. and 
amp, 1 W out on 432 MHz, 


40392 


7 


100 


RCA 


Useful to 12 MHz. Special flanged case 


2N3553 


7 


500 


RCA, MOT 


Popular HF/VHF power amp. and UHF osc. 3 W out 
on 144 MHz. Similar: 40280, 40290 


2N2631 


8.75 


200 


RCA 


An easy 7,5 W out on 50 MHz. 



76 



73 MAGAZINE 



The Circuit 

Efficient, clean-sounding transistor rf 
begins in the oscillator. Remember one 
basic rule: the transistor oscillator is a low 
power device. Tube tricks, such as 40 watt 
oscillators, just don't work with transistors. 
As the power to the oscillator is increased, 
clean keying and frequency stability are 
quickly lost. 

Shown in Fig. 1 . is the typical Pierce 
transistor crystal oscillator. Two com- 
ponents are of note, base bias resistor Rl 
and collector tank LI. Rl should be selected 
for the best keying characteristics. A 5K or 



XTAL 



X 




x 



^Cj 



m 




17 

-r c 4 



I 



6 



f77 /77 

Fig, 1. Typical Pierce crystal oscillator circuit* Cj." 
feedback capacitor; €% C4: rf bypass capacitors; 
C3; output tank capacitor; Ry. base bias resistor 
(see text); Lj; output tank coil (see text) usually 
ferrite* 

10K pot can be wired in during initial 
experimentation, adjusted, measured, and 
then replaced with the nearest fixed-value 
resistor. The value will usually be in the 
vicinity of 3K. Values shown in published 
circuits will seldom require adjustment. LI 
should similarly be tuned for the highest 
output that is consistant with good keying 
and stability. Even if the oscillator will not 
be keyed, as in a SSB rig, these adjustments 
should improve stability. 

Stable oscillation in vfo circuits is more 
difficult than in the simple crystal oscillator. 
The cost, though, of a simple vfo compares 
with the price of a few rocks, and the 
versatility of variable frequency is well 
worth the extra effort. The Clapp circuit is 
almost universally used, and for best sta- 
bility should be well shielded. Many fine vfo 
designs have appeared recently in 73. 

The vxo, or variable frequency crystal 
oscillator, is a good compromise between the 
crystal oscillator and the vfo. Shifts up to 25 
kHz are possible from a single crystal with 
rockbound stability. 

The simplicity of the typical transistor 
driver stage is yet another good reason for 
low oscillator input. Fig. 2 shows all that is 
actually necessary — an extra tank circuit, 
transistor, bypass capacitor, and bias resis- 



OSQLLAT0R 




Fig. 2. Typical transistor driver stage. L*2 : oscillator 
link; L%: output tank coil (see text);R2? base bias 
resistor (see text);C$: output tuning capacitor (see 
text); Cg: rf bypass capacitor. 



tor. In many cases the bias resistor will not 
be needed, as many transistors are capable of 
efficient "zero bias'* operation. If needed, its 
value will be very low, and a small (100 
ohm) pot can be used to adjust it for 
maximum power output, as explained above. 
Unlike the oscillator tank, output coil L3 is 
usually air-wound for higher efficiency, 
necessary because of the higher power level 
found in the driver. Therefore, tank tuning is 
done by capacitor C5, also tuned for maxi- 
mum power output. 

The selection of the transistor type for 
the driver is more critical than many builders 
realize. A type should be chosen that is 
incapable of overdriving the final amplifier 
The use of a higher power unit than neces- 
sary "cut back" to a low power level is 
dangerous, and often costly, as meters or 
lights are usually needed to monitor the 
drive. 

Completing the r/line, Fig. 3 is a simple 
transistor final Notable here are the 
paralleled transistors. While some may frown 
on paralleling in the output stage, it remains 
an inexpensive method to increase output. 
An attempt should be made to find two 
transistors of the same type with similar 



DRIVER 




L fe OUTPUT 



^C, 



Fig. 3. Transistor output stage. L4; driver link; L5: 
output tank coil; JLg: output link; R3; base bias 
resistor (see text); Qj, Q^: paralleled output 
transistors (see text); Cy; output tank tuning 
capacitor (see text); Cg: rf bypass capacitor. 



MARCH 1972 



77 



LEARN RADIO 




Album contains three 12" 
LP's 2VS hr. Instruction. 



THE EASY WAY! 

• No Books To Read 

• No Visual Gimmicks To 
Distract You 

• Just Listen And Learn 

Based on modern psychological 
techniques— This course will take 
you beyond 13 w.p.m. in 
LESS THAN HALF THE TIME? 
Available on magnetic tape, 
$9.95 - Cassette, SI 0.95 



EPSIIOH [§] RECORDS 



508 East Washington St., Areola, Illinois 61910 



KITS 



Sub Audible tone 




Compatible with all sub-audible tone systems such as 
Private Line, Channel Guard, Quiet Channel, etc. 

Glass epoxy PCB's & silicon xstrs throughout, 

Any reeds, except special dual coil types may be used 
Motorola, G.E., RCA, S.D.L., Bramco, etc. 

All are powered by 12 vdc. 

Use on any tone frequency 67 Hz to 250 Hz 

Small sire 1,5 x 4 x .75" 

Alt parts included except reed and reed socket 

Postpaid - Calif, residents add 5% sales tax 

COMMUNICATIONS SPECIALISTS 

P.O. Box 153 Brea CA 92621 



The ALPHA SEVENTY 
Power Amplifier Of The Seventies 







I 



Phone/write Don Payne, K4ID 
For a brochure or big trade-in on your gear 

PAYNE RADIO 

Box 525 Springfield, Tennessee 

days (615)384 5573 •nights (615)384-5643 



ARNOLD'S ENGRAVING 

Personalized 

ELECTRIC 

ON-THE-AIR 
SIGN 

WITH CALL 




WA2ZHA 



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110 VAC 




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ARNOLD'S ENGRAVING 

2041 LtitfM St. Pldgtwood. N.Y. 11227 



iii-circuit characteristics. Collector current, 
Ic, is the most important. 

Link coupling is shown in the final, as in 
the other stages, for interstage coupling. 
Tapped coils can also be used, although with 
adjustment, links prove more effective- 
Bias resistor R3 resembles the drivei 
resistor R2, and all comments apply. This 
value is not critical, as the resistor serves 
only to raise slightly the stage's efficiency by 
creating class C operating conditions, 

The final is almost always tuned for 
maximum output rather than Ic dip- C7 is 
simply adjusted for maximum meter or light 
indication, depending on the type of indi- 
cator used. The Ic should be monitored 
during the initial tune-up, to warn of exces- 
sive current. 

See the references at the end of the 
article for a list of recently published tran- 
sistor rf circuits. 

Obtaining Information 

Perhaps one of the most useful all-around 
guides to semiconductor products is the 
Allied Electronics Industrial Catalog. Specifi- 
cations and prices are given for thousands of 
current types. It can be obtained free on 
request from Allied Electronics, 100 N. 
Western Ave., Chicago, Illinois 60680. 

Information can also be obtained from 
the individual companies. Most transistor 
manufacturers distribute for a few cents 
product guides or free application notes. For 
several dollars complete specifications can be 
found in the large technical manuals. 

Transistor rf is here to stay. Take advan- 
tage of the low cost rf available with 
transistors - today* WA8ZEL 



Selected Articles 
W4BRS, "A Toroidal VFO," 73 April, 1967 
W1DTY, "An FET VFO for 80 Meters/ 1 73 May 

1967 
W1DTY, "Designing Transistor Oscillators/' 73 

August, 1967 

W1CER, "A Transistor 5-Watter for 80 and 40/' 
QST June, 1967 

W1CER, "50 Me, One Walter/ 1 QST June, 1 967 
W1CER, "An Experimental UHF Oscillator/ 1 , QST 

August, 1966 
K1UBA, 4t I60-Meter 'Solid Status\" QST April, 

1966 
K6RIL, "A Stable VFO for VHF or HF," 73 

November, 1966 
Wl JJL, "The Novice Pair," 73 December, 1966 
W0TKX, "Simple R.F. Output Circuitry Design for 

Transistors," CQ January, 1966 



78 



73MAGAZ1NE 



-. ^r TIT ^r ^^ ^H ^p ^p "^p 



V 



* 



V 



ft 

* 
ft 



V 

* 

ft 



V 
A 



V 

♦ 
ft 






•:♦ 
♦ 

♦ 
ft 

* 



ft 
ft 






**• 



1^ 



* 
ft 
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♦ 
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ft 

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»_• 



•_# 






FACSIMILE UNIT, compact 12x12x6", Used in 
many offices for 2-way messages. Complete with 
built-in ac 60 cy power supply. With schematic. 

Two for • ■...•. $27.50 

Each ....$14.95 




HALLICRAFTER TRANSCEIVER TR35A (fac- 
tory seconds) AM 2 to 9 MHz, 4 crysal controlled 
channels. 35 watt transmitter. Receiver is super 
het. This unit is solid state except the final tube. 
Also has a solid state I 2V dc or 1 10V ac supply. 
Unit may need some work. With schematic, as is, 
like new condition . ♦ . $39.50 



R390 COLLINS RECEIVER working & aligned 

...... $550.00 

Working, not aligned ............... $450.00 






16MM MOVIE CAMERA magazine load type 
complete with F3.5 lens. Motor driven. 




BC221 FREQUENCY METER 125 kHz to 20 
MHz in good condition with proper book $49.50 

APX6 TRANSCEIVER makes ideal 1215 MHz 
ham rig with complete conversion instructions. 



PRS3 MINE DETECTOR for detecting various 
metals including gold. Later type $49.50 



SPECIAL COLLINS 1000 watt final (actually 
this unit is a transmitter TRC75 or ARCS 8). Also 
has a 400 cy power supply , easily removed. 

Brand new . . . . . $ 1 50.00 

Or will trade 

RADAR TRANSCEIVER APQ41 X band with a 
4J50 magnetron and a 2K25 klystron with all 
tubes. Light and compact $39,50 

PRECISION VOLT AMP METER - Weston, 
Range 0-3-1 5-150V dc and 0-3-1 5 -30 A dc. With 
carrying case $1 2.50 



MODEL 14 TD with synch motor. The motor is 
in good condition. The rest for parts or for repair 

OUTDOOR SPEAKERS with treated cones for 
bad weather exposure. Encased in metal box 
4x4x3 $3.95 

URC4 compact VHF &. UHF WALKIE TALKIE 
6x3x1.5. Easily converts to 2 meters. Complete 
with directional antenna $35.00 



PRC6 banana shaped Army WALKIE TALKIE 

Freq 47 to 55 MHz. Compact & 



PRC10 back pack type WALKIE TALKIE size 
9X10X3". Frequency range 38 to 55 MHz. With 



A 






V 



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ft 



.!. 



*> 
♦ 

ft 
* 
♦ 
ft 
ft 
♦ 
♦ 

«% 



*** 

■:• 



* 

ft 
* 
ft 



V 

•> 

ft 
ft 



RT66 GRC FM Transceiver 20 to 28 MHz 

RT67 GRC FM Transceiver 27 to 39 MHz 

$49.50 

RT70 GRC FM Transceiver good for 6 meters. 
Compact 5x7x12". Good cond $39.50 



HS33 HEAD SET 600fi 
boom mike 



$4.95 



200 kHz $1.50 

1000 kHz $2.95 

10500 kHz $1.00 

11000 kHz $1.00 
12000 kHz $1.00 



CRYSTALS 



13000 kHz $1.00 
14000 kHz $1.00 
15000 kHz $1.00 
16000 kHz $1.00 
17000 kHz $1. 00 



ft 
ft 

ft 
* 



* 
* 



5 LEVfcL PUNCH TAPE READER, usable from 
0—250 wpm, depending on pulse rate to solenoid £ 
ea$7.95 * 



■ ■ 



TELETYPE RECEIVING SYSTEM consisting of 
a SP600-JX receiver & CV182, all mounted in a 

rack with cables & manual $295.00 

Or will trade % 
-ft 



& & ®Mm wss@E®@m 





1624 South Main Street Los Angeles CA 90015 




TERMS: Remittance in full or 25% deposit on COD order. Minimum order $5.00 FOB L.A. 



A. A. A . • 



v *;♦*> *>*:■*> *>■> **- •>#> *> •>*>*;• <**;• •>•■>■>*■>■>•> •> ♦ ♦ ♦*>*> •!••>•> •> •:* *> •>■> ♦ *>*i**i* •:•*!**> ♦♦♦+i**t**i**i**i*»>*;«>c* •>*:* •;••;• •> <•<■ «* 



M 



IMPOSSIBLE? BARGAINS IN SURPLUS ELECTRONICS AND OPTICS 




, 




SANKEN HYBRID AUDIO AMPLIFIERS 

AND SUPPLY KIT 

We have made a fortunate 

purchase of Sanken Audio 

Amplfier Hybrid Modules. With 

these you can build your own 

audio amplifiers at less than the 

price of discrete components. 

\ £l\** ^^2?^ ^ ^ Just add a power supply, and a 

k V^^jra v^ ^ja^^ chassis to act as a heat sink. 

m \d ^Smt V P^ Brand new units, in original 

A* ^^ ^m ^^ boxes, guaranteed by B and F, 

^k ^^Br Sanken and the Sanken U.S, 

distributor. Available in three 
sizes: 10 watts RMS (20 watts music power), 25 watts RMS (50 
watts M PJ and 50 watts RMS (100 watts MP.) per channel, 20 
page manufacturers instruction book included. Sanken amplifiers 
have proved so simple and reliable, that they are being used for 
industrial applications, such as servo amplifiers and wide band 
laboratory ampfif iers. 

D 10 Wan RMS Amplifier , , . . , $ 4.75 

D 25 Watt RMS Amplifier $14.75 

Q 50 Watt RMS Amplifier ....... $22.50 

D Complete kit for 100 watt rms stereo amplifier (200 watt 
music) including two 50 watt Sanken hybrids, all parts, 
instructions, and nice 1/16" thick black anodized and punched 

chassis » : »• v *'•■ •*•••'.•»*.♦« » »*♦»■■ ■ Soo.OO 
D Same for 50 watt rms stereo amplifier includes two 25 watt 

Sankens.etc S58.00 

D Same for 20 watt rms stereo, includes two 10 watt Sankens, 



7 SEGMENT READOUTS 



etc. 



. $30.00 




SUBMINIATURE TOGGLE SWITCHES 

These are nice, American made switches, of a size 
compatible with subminiature equipment and 
digital control panels. Available in two electrical 
configurations, conventional on-off SPDT, or 
on-off -on momentary SPDT. Specify which type. 
All brand new, at MZ catalog price. 
D Subminiature Switches (specify on-off or momentary) 

$1.00 each 

10 for $ 8.50 

100 for $7500 



THIS MONTHS SUPER SPECIAL! 

JENSEN HIGH COMPLIANCE SPEAKER SYSTEMS 

A local manufactur- 
er went out of the 
speaker enclosure 
business, and we 
were lucky enough 
to buy his inventory 
of Jensen high-corn- 
p I lance (acoustic 
suspension) speaker 
s y s t e ms . These 
systems consist of a 
12" extended range 
woofer, a hemi- 
spheric dome tweet^ 
m, plus crossover. 
The dome tweeter 
response extends in- 
to the supersonic. 
The dome shape provides an ideal polar pattern response. The 
system is ideal for use with our Sanken Amplifier Systems, or any 
system capable of putting out at least 20 watts rms per channel. 
Full instructions for cabinet construction are included. 

Single System (One Woofer, Tweeter and Crossover) . . $29.00 

Shipping weight 10 lbs. 

Stereo System (Two of Above) . . , . . $55.00 

Hi Compliance Woofer Only (8 lbs.) . . . . , $22,00 

Dome Tweeter only (3 lbs.) . . . . $5.75 





5 Volt 

23 ma/seg, 
100 K life 



A 



7 Segment Readouts, Two 
types are available, a large sue 
model with wire leads for PC 
Board Mounting illustrated at 
(A) and a small size 
tow-current version in a Dual 
In-Lme type package for 
miniature battery operated 
instruments illustrated at (B). 

n Large Size Readout 

(IHui. A) $3.45 

D Low Current Version 

(lllus, BJ . S3.25 

□ Complete counter kit, 
including 7490 decade 
counter, 7447 decoder and 
printed circuit board, and 
choice of either readout. 
Price . . . . $8.25 

G Complete counter as above, 
with 7475 latch, for storage. 
Price . . . . $10 25 



Complete Bi-directional counter, with 74192 instead of 

7490, for up- down counting , . $11.25 

n Complete Bi-directional counter, with latch for storage 
(74192 7475-7447) . . . . , $12.25 




5 Volt 
3 ma/seg ( 
50K life 





RADIATION METER ("Geiger Counter") 

You can buy a com 
plete radiation me- 
ter, complete with 
original instruction 
books, at less than 
the price of the 
meter movement a* 
lone. Range is 0.02 

kfl to 50 Roentgens/ 
K *ji# >ur. This is not 

sensitive enough for 
prospecting, but 
useful for other 
radiation measuring 
and monitoring pur- 
poses. If not used 
for its original func- 
tion, then the case, 

meter and battery holder alone are worth our asking price as a 

basis for building a metal locator, etc. Uses standard D cell and 

22.5 volt Battery. 

D Radiation Meter , , , . S9. 50 + $1.00 postage fir handling 

□ 80 PAGE CATALOG - Free with any order or send $0.25 



To oit r customers: 

B and F is moving to a new location: 119 Foster Street, Peabody, 
Mass. 01960 (same address, but different building). Our apologies 
to any customers who expert ced delays in shipments during the 
move, Our new expanded shipping and storage areas will allow us 
to service your order faster than ever before. Retail customers are 
now welcome at all working hours (Monday through Friday, 9 - 
5: Saturday, 9-3). Special few of a kind items are being cleared 
out, so come and visit our new location with twenty five thousand 
square feet of surplus bargains. 

ALL ITEMS {WHERE WEIGHT IS NOT SPECIFIED) 
POSTAGE PAID IN THE U. S. A, 

CHARGES WELCOME! 

Phone in charges to 617 531-5774 or 617 5322323 
BankAmericard - Mastercharge. $10.00 minimum. No C.O.D/s 

please, 

B.&F. ENTERPRISES 

Phone (617) 532 2323 
P.O. Box 44, Hathorne, Massachusetts 01937 



G&G CATALOG 

MILITARY ELECTRONICS 



24 PAGES, crammed with Gov't Surplut Electro nic Omar - thm Sywt 
bargain Buys In Americol It will pay you to I £| ||Q 2SC I 

for your copy - Refunded with your f*nt order, 

BC-645 TRANSCEIVER 15 tubes, 435 to 500 Mc, 
Easily adapted for 2 way voice or code on Horn, 
Mobile, Television Experimental, and Citizen* 
Bonds* With rubes, lets power supply efcf A AC 
in factory carton, BRAND NEW 910*99 

TRANSMITTER has 4 tubes: WE-316A, 2-6F6, 7F7 
RECEIVER has 11 rubes: 2-955, 4-7H7, 2-7Ee, 3-7F7 
RECEIVER I.F,: 40 Megacycle* 
SIZE: 10-1/2* x 13-1/2" x 4-1/2"* Sripg wt 25 lb*. 

SPECIAL PACKAGE OFFER: BC-645 Transceiver, Dynamotor and aft 
accessories, including mounting, UHF Antenna Assemblies, control box, 
complete set of connectors and ptuas. ^_ _ 

Brand New . . , , #26*95 




HEADSET Low impedance. With large chamois ear cushions. 
4-ft cord and plug. Reg* $12.50. Our Special Price £2*95 

Less ear cushions .,«*«««•• SI »95 

High impedance adaptor for above. . . $ .6° 



Free* 

Rinse 

RECEIVE*?. 

190 - 550 Kc . 
6 - 9 J Mc . 

1,5-3 Mc 

TRANSMITTERS 

4 - 5,3 Mc 
5.3- 7 Mc . 



Line 

Mew 



SCR-274-N, ARC*5 COMMAND SET HQ! 

Ekc. 
Tyo* Used 

Compete will* Tube* 

• 1 * ffV*4jJ » . * r ■ r <■ # IO|7J a ■ 

■ , T Du'Wj i . * ■ * | , ^^™ * * 

• * * R— 25 •»#••■'»« — 
Comoiet* wlin Tubes 

, &C-457 . . IS. 95 , . 

* B'C"4jO - - ■ + ♦ - * #O.Vj * > 



BStANO 
NEW 



— . . .$22,50 
$19.50- $21.50 

— .,,$11.95 

— ...J1..95 




TG-34A CODE KEYER, self -contained, automatic, 
reproduces code practice signals from paper tape. 
5 ta 12 WPM BuMt-in speaker, frand new with tech 
manual* takeup reel and AC line cord. . . . S 24*50 
Code practice topei For above F.U,R« 

BC 1206-C RECEIVER Aircraft Beacon Re- 
ceiver 200 to 400 Kc, Operates from 24V OC T.5A, 
Continuous tuning, vol control , on-off switch and 
phone jack. Very sensitive. Compact, 
Complete with tubes, NEW $12,50 



BC-604 FM TRANSMITTER 20 to 27.9 Mc 
Output appro* 30 watts, 10 crystal controlled 
channels. Complete with tubes, 

•rVCVT ....... ■■■■<. ....... ....p., 1^1 ^mmtm\m 





ARC-* 1 1 A Modern Q-5 Receiver 190-550 Khx , . 

ARC*R22 540 - 1600 Khz Receiver with tuning graph 
R-4/ARR-2 Receiver 234-258 Mhr, 11 tubes, NEW „ 



- • > ■ » • 



$1095 

$15.95 

$6-95 



BC-605 INTERPHONE AMPLIFIER, NEW $3.45 EXCUSED, ... $1.95 

TELEPHONE HANDSET, W.E. type . LIKE NEW $2.95 

SCR^522 TRANSMITTER^RECEIVER, with 18 tubee. LIKE NEW .$ 32.50 

AM-300/A1C PUSHPULL AMPLIFIER 

4-tube PP power amplifier with dynamotor, works on 

26 VDC . Automatic gain control » 

Shpg wt 15 lb*. LIKE NEW $3.95 



DUAL AMPLIFIER has two input circuits each 
feeding a single 6SN7GT twin rriode amplifier. 
Complete with 1 15V 60 cy, power supply 
using 6X5 GT rectifier. NEW $5*95 




AN/APR . 4Y FM I AM RECEIVER "FB" far Satellite Tracking I 
High precision lab instrument, for monitoring and 
measuring Frequency and relative tignal strength, 
38 to 4000 Mc. in 5 tuning ranges. For 110^60 cy- 
cle AC. Bull r- In power supply. Original circuit 
diagram included. Checked out, etiiei */% 

Perfect. LIKE NEW $S8.50 

AM tuning unln available for above. P,U.R. 





R48/TRC-8 UHF FM RECEIVER 230 to 250 Mc. Variabi, 

tuning, one band, 115/230 V 60 cy. Complete with speaker, phone 
jock, squelch circuit 2-1/2" meter for circuit test- 
ing; includes T 5 tubes: 8/6AG7, 9002, 5U4, 6V6, " 
VR-150, 6N7, 65N7, 6A17. Size 20 x 19 x Id". 
Weight 75 lbs. 
NEW . , , $34.50 




TV-1QAUHFTRANSVERTER avoc 

Made by Aircraft Radio Carp. Couples UHF Ant- 
enna to VHP transmitter dnj VNF receiver. Uses 
6 tubes: 4/5763 and 2/6201. Includes 8 crystals 
ranging from 233*8 Mc to 257.8 Mc. Size: llx 
4-1/2x4-5/8". Wt 5-1/2 lbs. 
LIKE NEW, with tubes and crystals $9,95 




R 20 RECEIVER 

Anode by Aircraft Radio Corp, works on 28 V, in- 
dues 4 tubes: 2/12AW6, 12AX7, 12AT7. Size: 
6-1/2x4-1/2x4-5/8-. 
LIKE NEW $7.50 




HANDMIKE 

Rugged, heavy ^iuty carbon handmike with press- 
to-tolk switch, Equipped with 4-ft cord cV phone 
plug. SPECIAL 

NEW, boxed Each $1.88 2 for $3,25 




2" DC VOLTMETER 

Mounts in 2-1/8" hole. Flange diameter 2-5/8*' 
Two scales; 0-15 and 0-600. Calibrated for use 
on steel panel. Standard brand. SPECIAL 

NEW, boxed Each $1.75 2 for S3,00 




BC-733 RECEIVER Receives radio signals 

being transmitted by US satellite on apprax, 106 
Mc. AM, crystal -control led on 6 preset freas. in 
108.3 to 110.3 Mc tvt*qq. Operates on 12/24 V 
DC & 220 VDC 80 Ma, Complete with 10 tubes. 
Can be converted to FM Receiver 

80 to 108 Mc. Exc.Used... $5.95 

BC-732A Control Box for above, NEW... 1.75 




T-41 / APS - 18 TRANSMITTER 
ANTENNA UNI designed for 115 V 800 to 
1400 cps, Tubee Included are two 15E and one 
151%. Complete with shock mounts 
and blower motor. 7x8x1 8 \ NEW $8.95 




BC-223AX TRANSMITTER 25 Watt, CW, MCW, 
Voice, Crystal control on 4 pre-selecred channel*, 
range 2000 to 5200 Kc by use of 3 plug in units, 
included. Complete. 
6RAND NEW $27.50 





IP-49A/ALA-2 INDICATOR 3" 

Front panel controls: Vertical Pos.; horizontal pas, 
Intensity, focus, gain, width, center freq. Pan, 
Operates on 115 V 380 to 1000 cps. 
Complete with tubes. LIKE NEW $27*50 




TG-5R TELEGRAPH SET tor code commun- 
ications or code practice. Portable, with hinged 
lid, Two or more units apmat^ up to 25 miles a- 
part, 8*11 call system, 1000 cycle howler, key, 
neaoplece,canvce case, book. 
Slxe 5-1/2k5-1/&i0-, NEW $8.95 




TELEPHONE TYPE RELAY 

Made by J.H.ftunnell, hoe adjustable 
sensitivity. 150 ohm coll, NEW 



$3.45 




APN-1 FM TRANSCEIVER 400-450 Mc. Freq. 

modulated by moving coil transducer , Eaiily con- 
verted for radio conlrol or 70 crns. Complete with 
14 tubes, dyn, 
BRAND r^€W $9*95 

AM-26/A1C PHASE INVERTER AMP. 

4-tube puihpull power amplifier. Carbon mike 
input, hi -I o Imp. output. Works on 24 VDC. Eas- 
ily converted to dandy 9-wott amplifier. Complete 
with tubes and dynamotor 
LIKE NEW $5.95 





WILLARD 2 -VOLT STORAGE BAnERY 

Rated at 20 Amp, -Hours, Model 20-2. Rechargeable. 
Compact nontptll construction. Lightweight polysty- 
rene container, 3*4x5 1/2". Shipped dry, usee standard 
electrolyte. Shipping Weight 3 lbs. NEW, each $2.79 




TERMS: 25'i Uvpoelt with order, belsnce C.O.O. -or- RemitUnce In lull. 
Minimum order |5.00 r.O. B. NYC. Subject to prior eele end price chinge 

GtG RADIO ELECTRONICS COMPANY 

47 Warren St (2nd Fl ) New York, NX 10007 Pk 212-267-4*05 



M 




UNIVERSAL 
DCU/DRIVER 




These universal counting modules have heavy 
duty outputs to drive all 7 segment displays 
requiring up to 15V and 40mA per segment. 
TTL used throughout. Requires 5 volt @ 120mA 
per module and any number of modules may be 
cascaded. Typ. count rate is 20 MH2 except the 
NR-3H which is 70 MHz. Will drive any display 
in this ad (not included). 



NR3 

NR-3A 

NR-3H 



Modulo 10 Counter . , 20 MHz. . $8.75 
Modulo 6 Counter , , 20 MHz. . . 8.75 
Modulo 10 Counter . . 70 MHz. . 10.50 



NR-3B Modulo 12 Counter . xlock 




12.95 



CRYSTAL 

FREQUENCY 

STANDARD 



The most versatile multi-digit counting kit ever 
offered!* Comes with 5 1/2 digits of counting 
and 7 segment decoding with the same heavy 
duty outputs as the NR-3. Typ. maximum count 
rate is 70 MHz, Each counting stage is com- 
pletely independent allowing a custom approach 
to your application. The "+" and "— " sign are 
great for DVM or over Hinder circuitry. The 
overrange stage also has an overflow latch and 

reset buffer. Displays not included. PC board is 

3 1/2" x 6". 

NR-3FM Multi-Stage Counting Unit . . . $39.95 

Contains a .002% crystal oscillator with TTL 
decade dividers to give output frequencies of 10, 
1 MHz, 100, 10,1 kHz, 100, 10, 1,& 0.1 Hz. Kit 
requires 5 volt supply @ 175mA. Uses low TC 
components and has zero-beat trimmer. Great 
for freq meter, digital clock etc, W/complete 
instructions. 

CR0-1D Crystal Frequency Standard . . . $21.95 




.: 




LINE 

CLOCK 

SOURCE 




ANALOG 

POWER 

SUPPLY 



LOGIC 

SUPPLY 

REGULATOR 



The DCC-2 derives precision gating and clock 
signals from the 60 Hz line. The input is a 
combination schmidt trigger and integrator 
which eliminate false triggering from line noise. 
The input is over-voltage protected and requires 
no adjustment, TTL compatible output frequen- 
cies are 10, 1, 0.1 , & 0.01667 {1 pulse/min.) Hz, 
PC board measures 1.2" x 3.5". 

DCC-2A Line Frequency Standard $12.95 

Power your OP-AMPS with this versatile, low 
cost, dual-polarity regulator. One control varies 
both outputs simultaneously over the range of 
0— 15V. Electronic current limiting may be set 
separately for each output over the range of 
25-200mA. Regulation is 0.1% and the ripple is 
below 3mV RMS. All parts conservatively rated 
for long life. 



APS-5A Op-amp Power Regulator . 



$12.95 



TR200 Transformer for APS-5A ......... 2,95 

Both kits have an output range of 3.3V to 5V 
with current limiting and short circuit shut 
down. Regulation is 1% and ripple & noise is 
lOmV RMS. Heavy duty components insure long 
life and allow rugged use. 



DPS-1 A Output current 0.6 A , . 
DPS-2A Output current 2.2 A . . 

TR 1 00 Transformer for DPS-1 A 
TR500 Transformer for DPS-2A 



. . . $6.95 



. . ♦ . 



2.29 
5.95 




$15.95 



LED READOUT MODULE - COUNTER - LATCH - DRIVER 



This new module has all the most desirable features 
required in counting and display. Fits 18 pin connec- 
tor, 5V supply. All TTL logic. 20 MHz count rate. 



Miniature 7 segment display mounts in 16 pin 
dual in-line socket. 5V operation at 8mA per 
segment. 100,000 hr. life. W/decimal pt. 

3015 Miniature Display - - .$3.45 .... 3/$ 10.00 

LARGER 7 segment display as pictured with the 
NR-3 series kits. Bright numerals can be seen 
even in direct sunlight. Mounts in 9 pin miniature 
socket supplied with the kits. 

2010 7 Segment Display . . 0-9 DP $4.45 





2020 As above except "1 



II4M liili it * r 



■ ** « V 



3.95 



LED 




RAM 



Electrically and physically identical to the 
popular MAN -1. Has higher light output 
than MAN-1. Includes LH decimal point. 
W/spec sheet & app information. 

LED700 7 Segment LED Display , . . $6,95 
(QUANTITY DISCOUNTS AVAILABLE] 

Build several instruments with this chip and little 
else. First really useful LSI chip for the experi- 
menter. Contains: 

* Four decade counters + overrange 

* Four 4 bit latches w/BCD outputs 

* Seven segment decoder 

* Display multiplexing circuitry 

* Two programmable oscillators 

* Single 5 volt supply at 5mA! ! ! 

* Inputs TTL compatible 

* Housed in 28 pin dual in-line pak 



The 1101 Random Access Memory (RAM) 
will store and readout 256 bits. The chip is 
TTL compatible and comes with a complete 
spec sheet w/appl ications. 



1101 256 Bit RAM 



- * 



it.** 3>o*yo 





LSI 



Comes with 16 p. booklet of specs & app 
notes. Booklet contains interfacing info on 
all seven segment displays made. 

5002 LSI Chip . . . $24.95 

5005 Booklet on 5002 only 1 .50 




MP-1 A 4000 Bit Core Plane 

MP-2A 16K Bit Core Stack a 



... 



$12 95 
. 47.50 



MPB-1 80 Page Core Memory Booklet .... 10.00 



At last! Noncritical memory planes for the 
experimenter. Made by Ampex for IBM spares. 
They were removed from NEW core stacks. The 
large 50 mil cores allow the use of the most 
inexpensive sense amps. The cores are in an 
80x50 array. All the necessary core specs are 
included with each plane. Available is an 80 page 
booklet describing an 8 bit x 1000 word memory 
using the MP-2A. Parts lists, schematics, and app 
notes are included in the booklet. 



WE STOCK THESE 
ITEMS & MORE 



INTEGRATED CIRCUITS 
TRANSISTORS & DIODES 
POWER TRANSFORMERS 
RESISTORS & CAPACITORS 
PC BOARD DRILLS 




ENVIRONMENTAL PRODUCTS 

BOX 406 

LAFAYETTE, IN 47902 



WE PAY POSTAGE 



317-743-1893 




2 Meter 



6 Meter 

GENERAL ELECTRIC . . . RCA . . . MOTOROLA 





GENERAL ELECTRIC 



s c 

U A 



R T 




VOICE COMMANDER 1 1 1 



FULLY SOLID STATE FM 

Transmitter -Receiver 



132 to 172 MHz 

1 WATT OUTPUT 

1/2 MICRO- VOLT SENSITIVITY 

Size: 9.5" x 5.3" x 1.7" 

High Performance, completely self- 
contained two-way FM radio. Com- 
pact, lightweight, easily operated 
and hand-carried. Housed in high- 
impact 2 -section case. All external 
hardware polished stainless steel. 

Includes rechargeable nickel cadmium 
battery pack and charger. .... 

$148<>o 

(Crystals & tuning, add $50) 

Lois of 5 less 10% ... ea. $133.20 
Lots of 10 less 15% , . ea. $125.80 

Proper chargers available separately. $15. 

each. 





r 



More than 15,000 items in stock. 
. ( . Send for new 1972 catalog. 



GREGORY ELECTRONICS CORP. 

The FM Used Equipment People 
243 Route 46, Saddle Brook, N. J. 07662 

Phone (201) 4899000 



TEST EQUIPMENT SPECIALS 

All in excellent condition, calibrated by IM.B.S. 
approved lab with Calibration Certificate, 

HEWLETT PACKARD 

120A Oscilloscope , SI 95.00 

120AR Oscilloscope 175.00 

1 20B Oscilloscope ^ . . * . ■ 225.00 

130A Oscilloscope . . , . , . , 250.00 

160B Oscilloscope with 2 plug-ins (military model) 

495,00 

170A Oscilloscope with 2 plug-Ins (military model) 

, mm 595.00 

1S5A Oscilloscope with 187A plug-in Amp. 595.00 

200CD Audio Oscillator 135.00 

201 C Audio Oscillator 125.00 

201 CR Audio Oscillator 100.00 

205AG Audio Oscillator . 250,00 

202A L.F. Function Generator 195.00 

21 2A Pulse Generator , 135.00 

330C Distortion Analyzer 195,00 

400D V/T.V.M. . , ,•...'■•■ 125.00 



100.00 
1 50.00 
125.00 
135.00 
100.00 



400DR V.T.V.M , . . 

400H V.T.V.M 

400HR V.T.V.M 

410B V.T.V.M 

410BR V.TW.M, , 

41 0C V.T.V.M 350.00 

412A V.T.V.M 195.00 

41 5B SWR Meter 115.00 

41 5C SWR Meter .................... 195.00 

430C R.F. Power Meter 95.00 

524D Frequency Counter . 395.00 

525 A Converter 10—100 MHz . 95.00 

525B Converter 100—220 MHz . . , . . 95.00 

526B Time Interval Unit 75.00 

540B Transfer Oscillator . 250.00 

603D Signal Generator . . . . 695.00 

61 2A Signal Generator 695.00 

614A Signal Generator 795.00 

61 6B Signal Generator . 695.00 

618B Signal Generator 795.00 

620A Signal Generator 895.00 

623B Microwave Test Set 995.00 

626A Signal Generator 1495.00 

650A Test Oscillator 195.00 

683C Sweep Osc. 2-4 Kmz 295.00 

684C Sweep Osc. 4—8 Kmz . 295.00 

71 2B Power Supply ............. 125.00 

71 5A Power Supply 75.00 

TEKTRONIX 

105A Sq. Wave Generator $135.00 

310A Oscilloscope 395.00 

515A Oscilloscope .....,..- 495.00 

516 Oscilloscope 495.00 

531 Oscilloscope 395.00 

533 Oscilloscope 450.00 

535 Oscilloscope . . . . 495.00 

541 Oscilloscope 595.00 

545B Oscilloscope 1250.00 

561 RM Oscilloscope 395.00 

Large variety of plug-ins also in stock .... P.U.R. 

MISC. TEST SETS 

SG-2/GRM-4 ILS Signal Gen. Equal to HP Boon- 
ton 232A $795.00 

SG-1/ARN-1 VOR Signal Gen. Equal to HP Boon- 
ion ^~ i i /"\ ......... ....... .».»»..*.. u"3.uu 

Collins 479S 3 VOR Audio Signal Generator 

.............. ■...* ■>■ ............. US'3 * \JKJ 

SG-13/ARN VOR -ILS Ramp Tester Equal to 

Collins 479T-2 . . . 795.00 

SG-12/U FM Signal Gen, 20-10O MHz . . . 695.00 



5CP1 
5BP4 
4-1 000 A 

4X1 50A 
4CX250B 



NEW TUBES & SOCKETS 

C*R. I * ............ , $ 4.95 

C.R.T 4.95 

Eimac SK-500 Airflow Socket & 

SK-506 chimney ....... 25.00 

Tubes . , 1 2.50 

U D SS ....... . . . ••«*■••*■ ID. \M\3 



TELETYPE EQUIPMENT 

M-15KSR Page Printer 
w/ Keyboard 8t Table 
M-28KSR Page Printer 
M 28ASR Teletypewriter 



Tested OK 

$ 199.50 
795.00 
1750.00 



CV 89A/URA-8A RTTY Audio Type Terminal 
Unit, Good condition, less cabinet 75.00 

COMMAND Receivers Transmitters 
RECEIVERS 

190-550KC Q 5er Good Condition $14.95 

Or Like New . . 19.95 

6-9MC 40 Meters Good Condition ........ 12.95 

XMTRS 

2.1 3MC T 18/ARC 5 New 4.95 

4-5.3MC T-20/ARC 5 Exl. Condition ....... 3.95 

4 5.3MC BC-475 New 5.95 

MD-7/ARC-5 Plate Modulator For Above Xmtrs 
Exl. Condition 4.95 

R-516/URR-27 — 

VHF AM MONITOR RECEIVER 
Just released, the Navy's most modern aircraft 
monitor, tunes 105 — 190MC. Has provision for one 
xtal channel or manual tuning. Similar to 
AN/URR-13. No conversion required, just hook it 
110VAC60CPS. Tested OK — excellent condition 
with schematic and instructions . . . $149.50 each 



IP 69/ALA-2 PAN ADAPTER 

This compact unit can be used with most Ham 
Receivers after conversion. Complete with con- 
version info and schematic. Good condition 
. $19.95 

2 METER AIRCRAFT MONITOR 
RECEIVER 130-150MC 

R-748/TRC-47 single channel AM crystal con- 
trolled 110V 60CPS, pwr supply & speaker built 
in, squelch, r-f gain, dual conversion modern 
design. Size 19* W x 5"H x 14"D for rack mtg. 
Supplied with schematic & hookup info. No 
conversion required. Exl condition ..... $29.95 

XMTRS - TRANSCEIVERS - RECRs 

T47/ART 13 2—1 SMC transmitter Less tubes — 
Good condition $14.95 

T-47/ART-13 with tubes Exl. Condition 49,95 

RT 18/ARC-1 transceiver 100-156Mc Exl. Condi- 
tion 39,95 

ARC-3 transmitter 24 channel 100-156Mc Exl. 
Condition 14.95 

BC 348 200 500KC & 1.5 18MC Reconditioned 
24V DC . 75.00 

ARB 190— 9O00KC Fair Condition with Control 
Box 19 95 

r^44/APR-4Y AM & FM* Excellent Condition 

49 95 

R-105/ARR-15 1.5— 18MC Collins Receiver, 

Good $49.95 

RBB 600-4000KC Recond. 115/1/60 100.00 

RBC 4-27MC Reconditioned 115/1/60. . . 10O.00 

ARC-3 Receiver 100— 156MC 24 Channel Exl. 

Condition 14.95 



MAYDAY * URGENTLY NEEDED I 

Top prices for AN/VRC-24, AN/TRC-68, AN/ARC-34, 51, 52, AN/PRC-77, Collins 6 1ST 
490- T-J, AN/URC-9, AN/SRC-20 & 21, plus all H.P., Tektronix, and lab grade test equip. 
Also all late model military electronic and radio gear. 

Write or Call Collect for top offer 213-875-2970 



Columbia Electronic Sales, Inc 




P.O. Box 9266, 7360 Atoll Ave., North Hollywood CA 91609 Tel (213) 875-2970 & 764-9030 



■ 



I 



ALE SALE SALE SALE SALE 





C847, 

C 874, 

C87/ART-13, 

C1 14 I nductor coil, 

C 1943/ ARC- 57, 

C5066/ARC-522, 

C 1904/ARC-27, 

C 161 loading coil, 



30 $7,50 ea 

40 $7,50 ea 

500 $.20 ea 

100 $.25 ea 

20 $4.50 ea 

12 $7.50 ea 

15 $10,00 ea 

100 $.25 ea. 



R 368/FRC-6 Receiver, 1 10V - 60 eye 

20 $15.00 ea. 



100 $8.50 
10 $35.00 

400 $4.50 
50 $4.50 

300 $.60 
20 $10.00 

150 $7.50 
50 $40.00 
50 $40,00 



R 5/ARN-7 Receiver, 

R 482A/URR-25, 

R445/ARN-30, 

R 443/ARN Receiver, 

R 22 Receiver for headset, 

R 89B/ARN-5 Receiver, 

R 316A/ARR-26, 

R 540/ARfSM4C, 

R 541/ARN 14D t 

R 101/ARN-6 Receiver, 100-1750 KC. 

100 $7,00 

R 23/ARC 5 Receiver, 190-550 KC, 

100 $8.75 
BC 453/ARC-5 Receiver, 190-550 KC, 

100 $8.75 
R 252B/ARN-14, 20 $20.00 

R 605/ARN-38, \Q $20.00 

R 13B/ARIM-30, 100 $4.50 

R1E/ARN-30, too $4-50 



ea. 
ea. 
ea, 
ea. 



ea. 
ea. 



ea. 



ea. 



ea. 



ea. 
ea. 
ea. 



RT 66/GRC 20^7.9 MC, 20 

RT 67/GRC 27-389, 20 

RT68/GRC 38-52-9, 20 

RT 82/APX-6, 4 

RT 175/PRC-9 with CY 744, 5 

RT 176/PRC-10 with CY 744, 12 

RT 196/PRC-6, 25 

RT 279/APX-25, 2 

RA63A Rectifier, 15 
RBM Rectifier power unit CAY 

watt, 115/1/60; 10 



$40.00 ea. 
$40.00 ea. 
$40.00 ea. 
$25.00 ea. 
$60.00 ea. 
$60.00 ea. 
$40.00 ea. 
$50.00 ea. 
$17.50 ea. 
20086; 80 
$15.00ea. 



BC 453 Receiver, 190-550 KC, 100 $9.50 ea. 
BC 458 Transmitter 5.3-7 mc, 100 $5.50 ea. 
BC 604 Transmitter 20-28 KC, new, 

100 $8.50 ea. 



BC 610 Insulator, 3G 11 10-88-4; 300 $,15 ea, 
BC 221 freq. meter, 10 $35.00 ea. 

BC 603 BC 683 

Filter Choke 2C4403A/F4, 500 $.10 ea, 

BC 1062A Range Computer, 1 17.5V @ 60 eye, 

2 $20.00 ea. 

BC 658B/VRC-3, 1 5 $3.50 ea. 

BC 348 Resistor 5905-638-5637, 200 $.10 ea. 

BD 110A swtod-C battery 50-60 eye. 30 mag- 



neto-! ph, 

BD 116A swbd, 

BE 51 outpost unit, 

BG 56 bags, 
BG 67, 
BG96, 
BG 153, 
BG 184, 
BG 188, 



10 $20.00 ea. 
4 $10.00 ea. 

10 $2.50 ea. 

500 $.75 ea. 
500 $.10 ea. 

50 $.60 ea. 
300 $-20 ea. 

50 $.40 ea. 
300 $-15 ea. 



Microphones: 

M95A/U microphone with boom, 200 $1.25 ea, 
M96/U microphone with boom, 200 $1 .25 ea. 
Canadian Microphone type RS-38 with F1 
transmitter, with push to talk switch, 

200 $1.00 ea. 
M 51/UR microphone, 
MC 419 lip microphone. 
Microphone cord with 
#19561 for URA; 
M 52 microphone, 
AIMBMC-1 microphone, 
M 29A/U, 



5000 $.30 ea. 

3000 $.30 ea, 

PL-68, JK-48-switch 

150 $1.25 ea. 
1000 $2.00 ea. 
1000 $.65 ea. 

500 $.40 ea. 



Controls: 

C433/GRC, 150 

C434/GRC, 150 

C 435/GRC less relays, 75 

C 434/ G RC less relays & generators. 

1000 
C 628/ARC-27, 360° max., 200 

C 22A Control, 500 

C 1398/ARC-38, 20 

C 527/APA-69, 50 



$2.75 ea. 

$5.50 ea. 

$.75 ea. 

$.40 ea. 

$2.50 ea 

$1 .50 ea 

$35.00 ea 

$9.50 ea 



msoiyii ©a 




SALE SALE SALE SALE SAL 



OAP Test Sets radar, 1 $9.50 ea. 

TS 13/AP Signal Generator, 115V 1 ph 60-80 

eye, 20 $25.00 ea. 

TS-15C/AP Ffuxometer, 40 $35.00 ea. 

AS 580A/ARN-30 Antenna, brand new, boxed, 

100 $9.50 ea. 
C 824/AIC-10 Controls; complete, 100 $4.50 ea. 
AS 578/ARA Antenna ) 

AS 578B/ Antenna ) 50 total $9.50 ea. 

A 13B Antenna ) 

T-51 Chest Sets with band straps, new, 

500 $-75 ea. 

PP-327B/GRC-9Y, new, 100 $25.00 ea. 

CD 802 Cord, 100 $1.00 ea. 

Headset HS-38, brand new, U.S. mfr with 2 ea. 

ANBhM, also cord and PL-354 plug. 

1000 $3.50 ea. 

CD 802 Cord, 100 $2.00 ea. 

CX 1 1 20 with plug, clamp 4' 6'V 1 50 $,75 ea. 
CX 2340, 100 $.95 ea. 

CX 2752- 17 ft long 2 #20, 150 $.95 ea. 

CX 3977 Cable, 7 cond #18 -6 ft, 100 $.95 ea. 
CX2753, 2 cond #22, 100 $.50 ea. 

CX 6367 (CO 212) with 2 plugs, clamps. 

500 



$.60 ea. 



164-4 connector on 27 ft cord CX 4639; 
164-20MS; 100 $1-50 ea. 

CD 807, 1 00 ft long. 1 50 $5,00 ea. 

U 77-U 78 on 30 ft cord. 100 $4.50 ea. 

Cable 3E7350-1-83-3; 14 cond # 16; 8 ft long 
with DPDM 12A 33S-1A, DPDM 12A 34P-1A 

75 $2.00 ea, 

RG 8A/U Cable. CG 399A, 100 ft long, new, 

100 $7.50 ea. 



H 60/PT receiver Cap, new. 
Diode IN 643. 



5000 $.10 ea. 
5000 $-05 ea. 



20 $25.00 ea. 
100 $2.50 ea. 



TA 182 Converters complete, 

TA 1 82 Cases, 

ID307/ARN Azimuth I ndicators; good, 

20 $12.50ea. 



MX 382A/GRA4; 33 ft guy rope, new, 

800 $-75 ea. 

2 ea: 164-3 connector on 9 ft cable, new, 

4000 . $6.00 ea. 
Heavy Cable 14 cond # 16; 3E7350-1-83-3 with 
2 connectors 

CD 316 cord with 2 plugs, PL-55, new, 700 $.95 ea. 
CX 4639 cable with 164-4 connector, 
164-201 -1S, 100 $1.25ea. 

CX 3639 27 ft long, 4 cond #16 
CG 530 F/U Cable 9 ft long with 2 each UG 
260D/U connectors, 100 $.95 ea. 



BC 453 B receivers 
BC 458 Transmitter 
Indicator flight command 
1270-767-6578, 

Throat mikes T-30, new. 
Navy Lip Mikes T-45, 

U 78/U Connector; 164-30, 

164-42, 

164-1 01 -3S, 

164 3 

UW 2020F800, 

164-9, 

164-10, 

2 ea: 164-3 on 9 ft cord, 

UG 254A, new. 

Plugs, PL- 147 
PL- 148 
PL-151A 
PL- 152 A 

PL-153A 

PL-154A 

PL- 156 A new. 



$7.50 ea. 

$5.00 ea. 

search and attack 

5 $40.00 ea. 

300 $.95 ea. 
200 $,95 ea. 

200 $1.00 ea. 
300 $1.00 ea. 



1100 $75 ea. 

700 $,50 ea. 

700 $1,50ea. 

400 $6.50 

1000 $25 ea. 



total 8000 S.05 ea. 



Canadian Royal Air Force Headset, 600 ohm 
with 2 receiver units - cord and microphone unit 
with push to talk switch, 300 $1 .50 ea. 

ARC-1 Transceiver, 100-156 MC-25 watt, com- 
plete with all tubes, 10 $20.00 ea. 

R 5A/ARIM-7 Receivers, 100-1500 KC 

ART-1 3 Transmitters complete 
BC 604 Transmitter FM 20-27 MC. 

Brand new 

UPM-6 Test Set, 10 

UPM-1 1/TS-738 Range Calibrator, 
50-1600 eye. 10 

UPM-1 8/TS-359 Test Set, 1 

UPM-19 Test Set complete, 2650 MC, 
115V AC at 1 .5 amp, 10 



. $9.50 ea, 
$25.00 ea". 

.$9.50 ea. 

$60.00 ea. 
115V at 
S60.00 ea. 
$40.00 ea. 
1 60 Watts, 
S60.00 ea. 



BC 221 with calibration book, 6 $40.00 ea. 

PL-68 on cords, 5 ft long, new, 2000 $.50 ea. 
ARC-3 Receiver, 8 channel. 100-1 56 MC $6.50 ea 
ARC-3 Transmitter: 8 channel, 100-156 MC - 

Both for $1 1 .00 — $6.50 ea. 

Bendix Amplifier #3611 with tubes and motor, 
24V at 1.2A; 220V at 0.60A . . $5.50 ea. 



Receiver Transmitter 

Anna Zampitella, 10,000 volt, ac dc, 2000 
amps, good shape, 1 only $2755.00 






StodMysa 



























1 T 



— 




arm 

COMMUNICATIONS 





MOTOROLA MOBILES 

T4 1 G/GG V 40-50 MHz 30W Vibrator Power 1 0" Case w/acc 
U41GGT 40-50 MHz 30W Transistor Pow 10" Case w/acc 

T43GGV 150 MHz 30W Vibrator Power 10" Case w/acc 

U44BBT3000 450 MHz 18W Transistor Pow 10" Case w/acc 



GENERAL ELECTRIC MOBILES 

ME 13 40-50 MHz 30W Vibrator Power 14" Case w/acc 

E 33 150 MHz 30W Vibrator Power 14" Case w/acc 



$ 99 
$109 



COMTRON 

960A DC 
960A AC 



150 MHz 30W T-Power all solid state rcvr 
Mobile Front Mount with ace. New as is 

150 MHz 30W 117V AC all solid state rcvr 
Base Station Table Top. New as is 



$159 
$189 



WRITE FOR FREE CATALOG 



Mann Guarantee 

Money refunded without question if equip- 
ment is returned within seven days from 
shipment, undamaged, freight prepaid. 



Conditions of Sale 

Unless otherwise specified, equipment is 
used, and is sold as*is. All items shipped 
FOB Tarzana. California. Crystals, ovens, 
antennas not included unless specifically 
stated in catalog. All equipment is sold on 
a first-come, first-served basis. 



arm communications 



18669 Ventura Blvd. 

Box 138 Tarzana, CA 91356 

(213) 342-8297 



2837 North 24th Street 
Phoenix, Ariz 85008 
(602) 955-4570 



• * « r 



♦ 



TEKTRONIX SCOPES 

555 with 21 A and 22A time base units and power supply 

545A with CA dual trace plug in 690 

585A with 82 dual trace plug in . 750 

551 with power supply 275 

581 275 

536 275 



PLUG INS 



G, 53B, L, 80, 53/54G 
\ t R, S, N, K * * , 



.*..*. 



* * 



>.*«..*+.. 



+ * * » 



$30 

50 



HP 



1 75A with 1 750A dual trace plug in 50 MC $475 

430C microwave power meter 115 

4 1 6A ratio meter 90 

GR 

1 209A unit oscillator $65 

1 208B unit oscillator 65 

1 21 5B unit oscillator 65 

Boonton model 710A linear ac to dc converter $135 

Hughes memoscope model 105 .235 



■ • • 



12c! 



TANALYTIC CAPS 

15uF35V 

15/iF 20V . . . . 12d 

12juF 75V . . .12cf 

Piston trimmer caps .8 pF — 5,5 pF . . . . 90<£ 

50 caps in a bag . . 90tf 

1 00 resistors in a bag 90d 

8 different trimmer caps in a bag , . . QQd 

IC MC 458P 8 for $1.00 

7.5 watt Ohmite rheostats, screw driver adj. (7.512, 511, 2512, 20012) 85d 

Variable inductors 3.0 jjlH — 9.0 juH .90d 

1 1SM23-T microswitches 15tf 

Thousands of other items too numerous to include. All new except microswitches. All 
equipment in good condition and guaranteed* 
Call, mail, or visit us, 

Tues. - Sat. 9-5:30 

TERMS RATED NET 30 DAYS, C.O.D. 25% 
MINIMUM ORDER $5.00 




4421 Chestnut Street 
Philadelphia PA 19104 
215-EV7-4555 




i,Y>,# 



'•' 



T^TTO 



for thin wallets! - 

JohnMeshna Jr. PO Bx 62 E. Lynn MA 01904 

Phone 617-595-2275 All material plus postage or shipping 



vj 



*w?- 



s 


C 


LI 


A 


R 


T 


P 


A 


L L I 


U 





S 


G 








MEMORY CORE STACK 

Complete brand new memory core stack 
w/diode matrix, 65, 536 core. Appear to 
be brand new $100 



LASER DIODE 3 WATT 

RCA TA-2628 w/specs 



■ * iOO 



BC 1031 PANADAPTER 450470 kHz "IF 

Operates from 115V AC 60 cycle. Gov't 
cost $300. Our price $45 good, used. 
Unused factory package w/spare tubes, 
book, AC cord $75 



LASER DISCHARGE CAPS 

Brand new Laser Storage high speed dis- 
charge caps. 40 juF at 3KV each $10 



ASCII KEYBOARD $50 

Like new, alpha-numeric keyboard, mag- 
netic reed switch keys, with encoder diode 
matrix in base. 



ROPE MEMORY MODULE SN7400 DIP IC, new 5/$1 

From APOLLO project $25 PHASE LOCK LOOPS your choice ... .$5 



1,000 /jF 450V CAPS 

For photo flash or linear power supplies 
S1 .50 each 10/S1 2 



565-566-567 

CV89A/URA-8A TELETYPE CONVERTER 

Audio type. Used S75 



Our newest and best catalog now available for the asking. After 20 years in the business, 
we know what to pick and choose for our customers and our current catalog offers you 
the finest of surplus bargains at the lowest prices as always. 96 pages of Super Mouth 
Watering exotic material to drool over. 



Transistors, brand new* factory marked. 



2N706 

2N1517 

2N17U 

2N2152 

2N221&A 

2N2222 

2N2369A 

2N2907A 

2N3013 

2N30S5 

2N3663 

MJ2250 

MJ2254 

2N5194 

TN-53 



83 
3W 

now 



3W 

soo 

1.2W 

i.sw 

1.2W 
115W 
200 

20W 
25W 
4GW 
800 



400 
70 



250 

2 50 
SOO 
125 

350 

700 



100 



N-S 
P-G 
N-S 
P-G 



N-S 
N-S 
N-S 
P-S 
NtS 

N-S 
S-N 
N-S 
P-S 

P-S 
N-S 



Use 



Sw 

VHF 
Pwr 

Pwr 

Sw 

Sw 

Sw 

Sw 

Sw 

Pwr 

Amp 

Pwr 

Pwr 

Amp 



Price 



4/K00 

4/1.00 

3/1.00 

1. 00 

3/K00 

6/1.00 

3/1.00 

3/1,00 

3/1.00 

1.50 




4/1,00 



StLCON DIODE SPECIALS 



1 Amp lOOOpiv 6/ 1.00 

2 Amp 1000 piv 6/1. <h 
2 Amp 1200 piv 4/1.00 
1 Amp 2000 piv 1.00 

1 Amp 3000 piv 1.25 



FULL WAVE BRIDGE MODULE 

2 Amp 400 PIV 1.00 "~" — 

3 Amp 1200 piv 1.35 *~™ 



100/10 P 00 
100/14,00 
100/20.00 



90 



73MAGAZINI 



Semiconductor Supermart 

• MOTOROLA • RCA • FAIRCHILD • NATIONAL • HEP • SIGNETICS • 



DIGITAL READOUT 




$3.50 



Actual Size 



At a price 
everyone 
can afford 

• Operates from 5 VDC 

• Same as TTL and DTL 

• Will last 250,000 hours 



SPECIAL OFFER 

• Digital readout 

• 8CD to 7 - Segment 
Decoder/driver 

• 7490 Decade Counter 

• 7475 Latch 
Only $8.50 



PLESSEY 

SL403D 
3.5 W AUDIO AMP IC 
HI-FI QUALITY 
$3.95 

with 12 pages of 
construction data 



The Mi Nitron readout is a miniature direct 
viewed incandescent filament display in a 16-pin 
DIP with a sealed front lens. Size and appearance 
is similar to LED readouts. The big difference is 
the price. 



NATIONAL DEVICES 

LM370 AGC/Squelch amp $4.85 

LM373 AM/FM/SSB strip $4.85 

LM309K 5V, 1 A regulator. 3-lead TO-3 case. 

Easy to use. Recommended for all TTL circuits 
$3.50 



MC 1 550 
CA3020 
C A 3020 A 
C A 3028 A 
C A 3001 
MC1306P 
MC1350P 
MC1357P 
MC 1 496 
MFC9020 
MFC4010 
MFC8040 
MC 1 303P 
MC 1 304P 



POPULAR IC's 

Motorola RF amp 

RCA % W audio 

RCA 1 audio 

RCA RF amp 

RCA 

Motorola Vi W audio 

High gain RF amp/ IF amp . . 
FM IF amp Quadrature det . 

Hard to find Bal. Mod 

Motorola 2 Watt audio 

Multi-purpose wide band amp 

Low noise preamp 

Dual Stereo preamp 

FM multiplexer stereo demod 



$1.80 
$3.07 
$3.92 
$1.77 
$6.66 
$1.10 
$1.15 
$2.25 
$3.25 
$2.50 
$1.25 
$1.50 
$2.75 
$4.95 



MPF102 JFET $.60 

MPF105/2N5459 JFET $.96 

MPF107/2N5486 JFET VHF/UHF $1.26 



MPF121 

MFE3007 

40673 

3N140 

3N141 



Low-cost dual gate VHF RF . . $.85 

Dual-gate $1.98 

$1.75 

Dual-gate $1.95 

Dual-gate $ 1 .85 



DIGITAL BARGAINS 

FACTORY FRESH TTL IC's 

FIRST QUALITY Tl & NATIONAL DEVICES 

7447 Decoder/driver for the digital readout or 

other 7 segment displays $2.25 

7400 gates $.35 

7441 NIXIE driver $1.95 

7490 decade counter $1 .40 

7475 quad latch $1.40 

7495 shift Reg $2.00 

7493 divide by 16 $1.90 

74121 monostable $1.80 

7473 dual flip-flop $.85 



MOTOROLA DIGITAL 

Quad 2-input RTL Gate . 

Dual Buffer RTL 

Hex Inverter RTL 

Dual J-K Flip-flop 

Dual Buffer RTL 

MC1013P85 MHz Flip-flop MECL . 
MC1027P 120 MHz Flip-flop MECL 

MC1023 MECL Clock driver 

MC4024 Dual VCO 

MC4044 Freq. Phase Det 



MC724 

MC788P 

MC789P 

MC790P 

MC799P 



$1.00 
$1.00 
$1.00 
$2.00 
$1.00 
$3.25 
$4.50 
$2.50 
$3.00 
$3.00 



PLESSEY INTEGRATED CIRCUITS 
GREAT FOR SSB RCVRS AND XMTRS 

SL610 low noise 150 MHz RF good AGC 

$5.65 

SL612 low distortion IF good AGC . . . $5.65 
SL621 AGC generator for SSB rcvrs . . . $8.30 

SL620 AGC gen. SL630 Audio $8.30 

SL630 multipurpose audio amp ...... $5.35 

SL640 top performing balanced mixer $10.88 
SL641 low noise rcvr mixer $10.88 

SIGNETICS PHASE LOCK LOOP 

NE561B Phase Lock Loop $9.50 

NE562B Phase Lock Loop $9.50 

NE565B Phase Lock Loop $9.50 

NE566V VCO (Function Generator) $9.50 

NE567V Tone Decoder (PLL) $9.50 



TRANSISTORS & DIODES 

MPS6571 

2N5188 

2N706 packet of 4 

2N2218 packet of 2 

1N4001 packet of 6 

1N4002 packet of 6 ..... 

1 N4004 packet of 6 



.$.60 
.$.79 
$1.00 
$1.00 
$1.00 
$1.00 
$1.00 



Please add 35£ for shipping 

Circuit Specialists 

Box 3047, Scottsdale, AZ 85257 

FACTORY AUTHORIZED DISTRIBUTOR FOR 

Motorola HEP - Circuit Stick - Plessey 
AH devices are first quality and are 
fully guaranteed. 



RADIO RECEIVERS AND TRANSMITTERS 
COLLINS R389/URR VLF RECEIVER TUNES 15KHZ TO 15O0KHZ, DIGITAL READ-OUT 

115V/60CY, 19" RACK MOUNT , .., .$385.00 

COLLINS R 3SS/URR, MILITARY VERSION OF 51J-3 RECEIVER, TUNES 500KH2 TO 

30.5MH2. 19" RACK MOUNT, 1 1&V/60CY , . . , ....,., T . $325,00 

HAMMARLUND SP^OOJX VLF RECEIVER. 10 TO 540KHZ IN 6 BANDS, 115V/60CY, 19" RACK 

MOUNT . , . . $295.00 

HAMMARLUND SP<600JX TUNES 54GKHZ TO 54MHZ IN 6 BAND, 1 1 5W60CY, 79" RACK 

™' ^*J \J I ™ P ■ m * ■* -■ » ■■ ■ ■ 9 i m <• 9 ♦ * ■ * 4 ■ * * w * • • • 4 • * "* 1 # ■ # * • » ■ •" •* + # j# # * ■# " * ' i • • ■ 1 ■ * ■ 4 ■* - m ™ ■ ■■ ■■ ■■ *P ^* " "^ ■ **'^» 

AN/URR 13 RECEIVER TUNEABLE UHF 225400MHZ, USED TO MONITOR MILITARY AND 

ASTRONAUT F RE OUENC1ES, AWCW P 115V/6DCY . , . . . . ...„,.... .$85.00 

AN/URR 27 RECEIVER TUNEABLE VHF 105-190MHZ. A COMPANION TO THE URR-13, USED 
TO MONITOR AIRCRAFT, 2 METERS, CAN SLOPE TUNE FM STATIONS, AM/CW, 

BC 348 RECEIVER, TUNES 200 500KHZ AND 1.5 TO 18MHZ, 28 VOLT DYNAMOTOR EASILY 

CONVERTS BY BUILDING 115V/60CV POWER SUPPLY . $65.00 

R 109/GRC RECEIVER 27 TO 389MHZ FM, TAKES PP 1175, 115V/60CY P/S 

TO OPERATE . . . t . ' $37.50 

PP-1175/SR POWER SUPPLY 115V/60CY, USED TO POWER CRC EQUIPMENT + . $32,50 

COLLINS 18S-4 TRANSCEIVER, 10 CHANNEL CRYSTAL CONTROLLED FROM 2 TO 1SMH2 

100 WATTS OUTPUT, AM/CW, 811 MODULATORS TO 813 FINAL, OPERATE FROM 28VDC 

DYNAMOTOR, EASILY CONVERTS BY BUILDING 750V TO 1200V DC POWER SUPPLY. IDEAL 

FOR NOVICE. MARS, RTTY OR ANYONE NEEDING CRYSTAL CONTROL OPERATION. A 
TERRff IC SUV ^cc nr\ 

RT176/PRC 10 FM BACK-PACK TRANSCEIVER, 38 TO 54.9MHZ, 1 WATT OUTPUT, WITH 
BATTERY CASE, LESS BATTERY. TAKES 1.5V, 07%, 135V DC. WILL DRIVE A LINEAR, $32.50 
1-1963, A LOW POWER TRANSMITTER WITH UNCALIBHATED OUTPUT USED TO 
DETF HMINE FREQUENCY LIMITS OF RADIO RECEIVERS, RANGE 140 TO 235 MHZ, TAKES 

1.5V AND 135V DC BATTERY, NOT SUPPLIED ! , . .$12.50 

URC-11 EMERGENCY HANDIE TALKIE, 243MHZ LESS 1.5 AND 135V BATTERY. IDEAL FOR 

AIRCRAFT. MARINE OR 220MHZ CONVERSION , , , SEE MAY '69 CO + . , .$14.50 

BC 709C INTERPHONE AMPLIFIER, USED IN AIRCRAFT TRAINERS, PILOT TO STUDENT, 
TAKES STANDARD FLASHLIGHT BATTERIES. JDEAL FOR PLANE, CAMPER, TRAILER, 

BOAT. HOUSE, FOR 2 WAY COMMUNICATION ... . f ... $3,00 

COLLINS 5U-4 RECEIVER 550KHZ TO 30MHZ SUPPLIED WITH 3 AND 6KC MECHANICAL 

FILTERS, 19" RACK MOUNT. 1 15V/60CY $550,00 

BC 625 VHF TRANSMITTER, 100 -166MHZ, CRYSTAL CONTROLLED IN FOUR PRESET 

CHANNELS, 28V DC, SEE SURPLUS CON VE RSION BOOK . . $18.50 

COLLINS TRC 75 RADIO SET, AM, CW, SSB, RTTY, 2 TO 29,999, POWER OUTPUT 2G0QW PEP, 
CONSISTS OF RECEIVER, TRANSMITTER, CONTROL HEAD, RTTY-CQNVERTER, ANTENNA 
COUPLER, ALL WIRED IN WATERPROOF CONTAINER THAT WAS MOUNTED ON REAR OF 

ARMY JEEPS, ORIGINAL COST $18,000. A BEAUTIFUL SYSTEM, PRICE 3950.O0 OR 

. , . WILL TRADE FOR OTHER COLLINS OR MILITARY SURPLUS. 
ARN-7 RADIO COMPASS RECEIVER, RECEPTION AM, CW, MCW AND VOICE. FRED RANGE 

100 TO 1750KHZ IN 4 BANDS •«,*.. $9.95 

ARN-14 OMNI RECEIVER 106.1 TO 135.9MHZ RECEIVES LOCALIZER TONE, LOCALIZER 

PHASE, OMNI DIRECTONAL RANGE AND VOICE $32.50 

GPR 90 RECEIVER .54-31MHZ, BUILT-IN CRYSTAL CALIBRATOR, AM, CW, MCW, FSK, AND 
SSB, 19 RACK MOUN1 ..*.*,., * f <,...._..... $275.00 



FREQUENCY MEASURING TEST EQUIPMENT 
LAMPKIN 105B, 100KHZ TO 175MHZ, BUILT-IN CRYSTAL CALIBRATOR, ACCURACY 

0.0025%, WITH ORIGINAL CALIBRATION CHART $145.00 

AN/URM-32, 125KHZ TO 1000MH2 CW, MCW. INTERNAL MODULATION 600 TO 1200 CY RF 
INPUT 0,1V: OUTPUT 100MV IN 50 OHMS, AUDIO OUTPUT 600 OHMS, ACCURACY 0.(5l%, 
INTERNAL CRYSTALS 1 AND 5MHZ PER SECOND, LESS BATTERIES, B+ 121,5VDC, A+ 

» ■ ^* V L-/ W> ■ ■vi*il#ti1-l + * + lf tiii*dd*i-iiii--hi-i* w*»*»mmaittti *i*fc*-ii-a ■ ■*■. + ■-■■-■■■■ w *# *» v ■ ^ %J 

HP524B FREQUENCY COUNTER, BASE FREQ 10HZ TO 10MHZ ( 6 VERTICAL READ-OUTS 
AND 2 METERS GIVING B DIGIT READ-OUT, EXTEND RANGE TO 510MHZ WITH 525 SERIES 

P^ ■"■ U ^fcJ '"I I ¥ *J ■ ■tf*tf-b. + ll-.. ■ ■■■•kfrtf*- ! F>l4*V + lPI P*i-#i*ll I ¥i*"H"PP ■¥■■»¥■■■ ■*■■ ■■ ■ ■ - ri *P ■*- *-■ ** ■ V» *# 

HP524C FREQUENCY COUNTER, BASE FREQ 10HZ TO 10MHZ, 8 DIGIT NIXIE READOUT 
EXTEND RANGE TO 510MHZ WITH 525 SERIES PLUG INS .... $375,00 



OSCILLOSCOPES 
OS^B/U, 3RPI TUBE, GENERAL PURPOSE. DC TO 2MNZ, PORTABLE CARRYING CASE, 

1 15V/60CY , $59.50 

USM 24 2HZ TO 8MHZ VERTICAL RESPONSE SENSITIVITY 50MV, TRIGGERED SWEEP, 

BUILT 4N TRIGGER PULSES AND MARKERS, 3" CRT , . . . , $95.00 

USM-32 10HZ TO 4MHZ, J VOLT SENSITIVITY, BUILT IN MARKERS, SWEEP 5MHZ TO 

100KHZ # , , . . _ , . , $95.00 

USM^I, MILITARY VERSION OF TEKTRONIX 536 WITH DUAL TRACE PLUG-IN $445,00 

TEKTRONIX PLUG^INS. MODELS K. E, OR G . . . YOUR CHOICE , , . , ,$45,00 EA. 

TS-34/AP PORTABLE OSCILLOSCOPE. 2PPI WITH 2X MAGNIFICATION LENS, VERTICAL AMP 

FLAT 30CPS TO 1MHZ, A GOOD PRECISION SCOPE . . , , , . , $34,00 

OS~57/U3M-38 OSCILLOSCOPE 10H2 6MHZ, 3'' CRT, SWEEP TIME 1 100.000MSEC 

TRIGGERED ON PERJOOIC, VERTICAL CALIBRATOR, BUILT-IN TIMING MARKERS .$95.00 

GENERAL TEST EQUIPMENT 
HF* 335B FM MONITOR. HAS TWO PANEL METERS TO SHOW CARRIER DEVIATION AND 
PERCENTAGE OF MODULATION WITH LAMP TO INDICATE PEAK MODULATION. IDEAL 

FOR RADIO STATION OR SHOP , $225.00 

GR-544B MEGOHM BRIDGE, COMBINATION WHEATSTONE BRIDGE AND VTVM, RANGE 0.1 

TO 1M MEGOHMS, FINE FOR LAB $39.00 

UPM-6B TRANSPONDER TEST SET, 980 1175MHZ, USE TO MAKE POWER AND SENSITIVITY 

ON PULSE TYPE EQUIPMENT; F AA APPROVED . . $175.00 

IE-36 TEST SET IN PORTABLE CASE, USED FOR TESTING RECEIVER SENSfTIVITY. 

MODULATION REMOTE SWITCHING, CHANNE L SE LECTION CIRCUITS . $17,50 

ME-11/U TERMALINE RF WATTMETER; MILITARY VERSION OF BIRD 611, 60 WATT DUAL 
RANGE 0-15/0^60, 30 TO 500MHZ, EXCELLENT FOR AM/FM MEASUREMENT .,,...., $65.00 
SG-299D/U SOUAREWAVE GENERATOR, A WIDE RANGE 1HZ TO 1MH2 CONTINUOUS 
COVERAGE. USE WITH ANY OSCILLOSCOPE TO DETERMINE FREQUENCY RESPONSE AND 
PHASE SHIFT CHARACTERISTICS OF VIDEO AND AUDIO AMPLIFIERS, MILITARY VERSJON 
OF HP 21 1 A $39,50 

STODOART R^F.L RECEIVER NM40A FREQUENCY 30HZ TO isKHZ, COMPLETE WITH 

POWER SUPPLY, LESS ANTENNAS , $125.00 

STODOART URM-6 RECEIVER, SAME AS NM-10A 10250KHZ, COMPLETE WITH POWER 

SUPPLY, ANTENNAS AND CABLES, TRIPOD $175.00 

BALLANTINE 300 VTVM; 10HZ TO 150KHZ RANGE, 1MV TO 100 VOLTS IN 6 RANGES, LOG 

ARITHMIC SCALE 1 10DB, ACCURACY 2% ,, $29.50 

TS-382/U AUDIO OSCILLATOR, TO 20OKHZ, WITH 60 AND 400 CYCLES REED FREQUENCY 

METER CHECK POINT. A FINE LAB INSTRUMENT , ,$79.50 

HP 218A DIGITAL DELAY GENERATOR WITH 219B DUAL PULSE UNIT. HAS VARIABLE 
GATE GENERATOR FOR WORK WITH D»GITAL COMPUTERS AND COUNTERS, A TIME 
INTERVAL GENERATOR FOR CALIBRATING TIME BASES, DELAY LINES, RADAR RANGES. 

AND PRECISION SWEEP DELAYS , , . , . „ ....,, $750.00 

TRACOR CARDIOID UNIT MODEL 6>2, USED TO MEASURE VLF ENERGY BEING RECEIVED 
ALONG SHORT GREAT CIRCLE PATH AND LONG GREAT CIRCLE PATH BETWEEN 
TRANSMITTER AND RECEIVER. AFTER PATH IS SELECTED NORMAL PHASE TRACKING OF 
VLF ENERGY CAN BE MAINTAINED. FREQUENCY RANGE 10 TO 39KHZ AND 60KH2, 50 
OHMS. ALL SOLID STATE. TAKES 10VDC REGULATED POWER SUPPLY, NOT SUPPLIED. A 
VERY INTERESTING UNIT FOR VLF EXPERIMENTS. THE OUTPUT OF THE CARDIOID UNIT 
IS CONNECTED TO THE ANTENNA INPUT CONNECTOR OF ANY VLF RECEIVER .... $32,50 
TS 330/TSM CRYSTAL IMPEDANCE METER FREQ RANGE 1-15MHZ, RESISTANCE RANGE 

0-9900 OHMS, CAPACITANCE RANGE 12 TO 110MMF ,,,,,, $65.00 

TS-592/UPM 15 PULSE GENERATOR PRF 50 TO 10,000PPS OUTPUT .002 TO 200 VOLTS .25 

TO 2500 OHM IMPEOANCE , $49.00 

TS'148/UPM-33 SPECTRUM ANALYZER - RANGE 8470 - 9630MHZ, SWEEP WIDTH 10-30MHZ 
VARIABLE, FREQUENCY SWEEP 40^50MHZ IF BANDWIDTH 50KHZ. PERFECT FOR ANY 

■ * ^^ vj ^^ n w \j n ^v .»>*...«..#.. * a »#■.."..... ...... *»**.* ...»■• 3 *j .*"j 

TS 505/U VTVM: 250VAC, IOOOVDC, 0-1000M OHM RESISTANCE MEASUREMENT, AC 
FREQUENCY RESPONSE 30HZ 500MHZ, HIGH INPUT IMPEDANCE, PORTABLE 

RUGGEDIZED CONSTRUCTION COMPLETE WITH PROBE , $65.00 

TS 723/U DISTORTION ANALYZER. 20HZ TO 20KHZ FREQUENCY RANGE, MEASURES 
DISTORTION DOWN TO .1%. BUILT-IN VTVM WITH FULL SCALE READING OF .03 300V 
RMS, DS: -30 to +50. MILITARY VERSION OF HP330B . . ......,,.. $175.00 



»•,«».,,»,. 



* ■ f ' - • • 



i * 4 m * • * 



• ■ • ■ 



■ ■ ■ , 



■i ■ ■ 



. . . • . 



i * • * li 



* I , ■ 



i * ■ * * 



HP524D BASE FREQ 10HZ TO 10MHZ B DIGIT VERTICAL READ-OUT. 525 SEHI ES PLUG INS 

EXTEND RANGE TO 510MHZ , , , .,.,,. $295.00 

FREQUENCY CONVERTER PLUG-INS FOR HP&24 B, C, D, USM-26, FR3S r AND 
NORTHEASTERN; 

HP-525A 10 100 MHZ 

HP 525B 100 220MHZ 

HP-525C 100S10MHZ 

HP 526A VIDEO AMPLIFIER 

HP526BTIME INTE RVAL PLUG IN 

HP 526C PERIOD PLUG IN 
HP540B TRANSFER OSCILLATOR 10MHZ TO 12,4GH2, EXTENDS FREQUENCY 

MEASUREMENTS WHEN USED WITH COUNTERS COVERING 10O-2OOMHZ $245 00 

GERTSCH FM 3. RANGE 20 10O0MHZ, ,001% ACCURACY. WILL ALSO GENERATE SIGNALS 

OVER THIS RANGE , $165.00 

GMQ-20 WIND SPEED AND DIRECTION RECORDER, RECORDS WIND SPEED 0-120 KNOTS 
ANO DIRECTION THROUGH 360 DEGREES. ON CHART, 116V/60CY ..$27,50 



"»!*'• 



+ ► *****•*■» 



, * , r , h r 



.+ ,..,, 



********** 



. $69.50 
. $85.00 
$195.00 
. $S5 + 00 
. $65,00 
. $65.00 



STRIPPER SPECIALS 
FOR THOSE WHO LIKE TO STRIP OUT EQUIPMENT FOR RESISTORS, CAPACITORS, TUBES 
SOCKETS, TRANSISTORS, CHOKES, HARDWARE, WIRE, CHASSIS, CIRCUIT BOARDS, WE 
HAVE SELECTED A GOOD ASSORTMENT OF MILITARY SURPLUS EQUIPMENT LOADED 
WITH COMPONENTS FOR STRIPPING. YOU WILL HAVE MANY HOURS OF ENJOYMENT; 
GUARANTEED TO SATISFY YOU. ORIGINAL COST IN THE THOUSANDS, 100 LB, ASSORT 
MENT SHIPPED PRE4»AJD MOTOR FREIGHT FOR . $32.50. GOOD IN USA ONLY, 



SIGNAL GENERATORS 
TS413/U 75KHZ TO 40MHZ IN 6 BANDS, PRECISE CALIBRATION FROM 1MH2 CRYSTAL 
OSCILLATOR HAS % MODULATION METER, CW OR AM 400/1000CPS VARIABLE 0-50% AND 
RF LEVEL METER O TO 1.0V, IDEAL FOR AMATEUR, MARINE, AIRCRAFT AND HOBBYIST 
FOR IF AND RECEIVERTRANSMITTER ALIGNMENT, OR DEVELOPMENT WORK , . . . $89,50 
SG 557/URM -52B 3800 THRU 7&00MHZ, 1 15W60CY Ml LITAR Y VERSION OF HP618B $245.00 
TS^*18/U 400 TO 1000MHZ. AM, CW, PM, POWER OUTPUT 1MW. A POPULAR SET WITH THE 

FM SHOPS FOR UHF WORK ,:,-,,, **♦.,..« $225.00 

TS 497/URR, G RANGES 2 TO 400MHZ r MILITARY VERSION OF MEASUREMENTS MODEL 80, 



0.1 TO 100,OOOMV 



4****1 » * * 



■ * • f * 



.$175.00 



SG 12/U, FM, 20 to 100MHZ. USED BY MILITARY FOR ALIGNMENT OF GRC FM EQUIPMENT. 

PERFECT FOR LOW BAND FM WORK , . . , . $275.00 

SG-1A7ARN WITH PP 348, MILITARY VERSION OF THE 0OONTON 211A, COVERS BS TO 

140MHZ, A POPULAR UNIT IN ALL AIRCRAFT RADIO SHOPS .*,...-., $650,00 

TS403/U 18004000MHZ ±1%, CW, FM,PM, PRR 40 TO 40,000 PPS, POWER OUTPUT 1MW.Q TO 
-127DBM, VARIABLE VOLTAGE OUTPUT .1 TO 224,0OOMV, MILITARY VERSION OF HP 

SG-47/URM 16 10MH2 TO 440MHZ in 12 BANDS, CALIBRATE OUTPUT 6MV TO 10,000MV, 
50 OHMS, INTERNAL MODULATION AM/FM 400 TO 10OOCY, EXTERNAL 20 TO 20,0O0CY. 

0.5% ACCURACY, ,002% WITH INTE RNAL CRYSTAL CALIBRATOR $345.00 

AN/URM 25, 10KHZ TO 50MH2 IN 9 BANDS INTERNAL MODULATION 0-50%, 100-1&/OOQCY; 
OUTPUT VOLTAGE IMV-0,1 VOLT, 50 OHM LOAD, AM/CW ACCURACY .5%, 12 POSITION 

ATTENUATION SELECTOR *.*•..,,.••,,..* . * * ,..,,., ....,.,,.. $225,00 

TS-419/URMh64, 900 TO 210OMHZ, CW/PM OUTPUT TO -120 DBM, _2MV INTO 500 OHMS, 
PRR 40 TO 4,000 PPS DELAY TIME 3 TO 300 USEC SIMILAR TO HP 614A AND ARC H-12, 

IDEAL FOR RADIO, RADAR, AND TRANSPONDER WORK . . , V- ~ . * $225.00 

AN/URM35, 4,450 TO 8 ( 00OMH2, CW/PM USED TO CHECK BROAD BAND RADAR 

RECEIVERS, ANTENNA TRANSMISSION LINES AND INDICATORS $37,50 

AN/URM-26, 4MHZ TO 405MHZ IN 6 BANOS AM/CW/MCW/PM, MODULATION TO 50%, 
INTERNAL 400 TO 1,0O0CY. EXTERNAL 100 TO 20,00OCY, RF OUTPUT ,1 TO 1O0,O00MV 
INTO 50 OHMS, ACCURACY .5% ..,,.. * .. - ♦ $225.00 



ATTENTION: LINEAR AMPLIFIER BUILDERS 
B & W 850A PI-NET INDUCTOR, DESIGNED FOR 80 1 METER AMATEUR BANDS, PLATE 
LOAD IMPEDANCE 2500-6000 OHMS, USED FOR SINGLE AND PARALLEL FED TUBES 
SERIES FED CIRCUITS, 813, 4-12B, 4-400, 4 1000 RATED 1000 WATTS NEW FACTORY 

BOXED . . . . , , . , , $59.50 

B & W 852 PI-NET INDUCTOR, DESIGNED FOR 80-10 METER AMATEUR BANDS, PLATE 
LOAD IMPEDANCE 2000^000 OHMS, USED FOR SINGLE OR PARALLEL TUBES, SERIES OR 
SHUNT FED CIRCUITS, 34002, 3 500Z f 3 10002, 4CX100OA ETC., RATED 1000 WATTS. NEW 

FACTORY BOXED *.,... ..,,__.. $59.50 

30 AlVIP GROUNDED GRID FILAMENT CHOKE, B1FILAR TYPE 1/2" x 7 1/2" LONG. USE WITH 

PAIR OF 4 2S0A, 4-400A, 3^4002, 3 5002,813*, OR SINGLE 4 1000A r 3 1 OOOZ $8 50 

JENNINGS UCS 10 30OMMFD VACUUM VARIABLE CAPACITOR 7.5KV WITH GEAR DRIVE 

TRAIN AND MOUNTING BRACKET, POPULAR FOR LINEAR BUILDING , , , $29.50 

NEW FACTORY EIMAC YELLOW BOXED TUBES, FACTORY GUARANTEED 

EIMAC 3-400Z , , , $36.00 

t I IVI r^.\^ .J | UUU£ .*««<#ll. 4. b. 4*|, *!,,*, »■■,!,■»,*, ■■■ ■ , , | ■ . i . | ( ipOS.UU 

EIMAC 4 400A , . . , . , h . $49,00 

EIMAC 4-400C •.,,., , , , . . , * $58,00 

EIMAC 4 10O0A , $130,00 

C I IV! ML* fluA - I UUUA • * * * t * • « t » « * • * t * t * t * * * » ■ • .. ■ • * ^ * * « 4 . * t * v ., . t .* * . -t * * * *. * * * » $ ldw ,UO 

EIMAC 4CX1500A , . , , $200.00 

EIMAC SK-510 SOCKET 3-1 OOOZ, 4-1 000 A , . . , , , . . . $10.50 

EIMAC SK-410 SOCKET 3-400Z, 3 5002 , , ( , .-, $10.50 

EIMAC SK-650 SOCKET 4X150A, 4CX250B, NO SCREEN BY-PASS , . . , . , $12.00 

EIMAC SK-620 SOCKET 4X150A, 4CX250B, HAS SCREEN BY-PASS $14,00 

EIMAC SK-516CHIMENY FOR 3 1 OOOZ ,,*.,.,. $12.00 

EIMAC SK^416 CHIMNEY FOR 3 400Z, 3 500Z , . , _ $7.00 

EIMAC SK-626 CHIMNEY FOR SK-6B0, SK^620, 4X 1S0A, 4CX250B , $2,00 

EfMAC HR6 HEAT DISSIPATING PLATE CAP FOR 4-65A, 4-125, 4-400 ETC $2.20 

EIMAC HRnS HEAT DISSIPATING PLATE CAP FOR 3-1000Z, 4-1 000A ..",..., $2.85 

SEND NEEDS FOR OTHER EIMAC TUBES AND SOCKETS, 



572B/T160L TUBES BY CETRON, NEW FACTORY BOXED AND GUARANTEED 



$16.50 



MISCELLANEOUS EQUIPMENT 

AN/PRS-3 MINE DETECTING SET IN SHIPPING CASE, A POPULAR UNIT USED FOR 
LOCATING RELICS AND LOST ITEMS. CAN BE USED AROUND SALT WATER AND IRON 
SOIL, GIVES METER READING AND TONE. TAKES STANDARD BATTE RIES, NOT SUPPLI ED 

ORIGINAL COST OVER $800.00. HAVE FUN WITH THIS, SPECIAL AT , $59.50 

PANORAMIC INDICATOR IP-259/U, MILITARY VERSION OF SB-8A TYPE T*200, 400*600KHZ 

IF INPUT, 5 INCH CRT, COMPLETE WITH PS 8 1 15V/60CY POWER SUPPLY . . . , $119.00 

CV^89/URA^B RTTY AUDIO TYPE CONVERTER, A POPULAR UNIT WITH BUILT-IN SCOPE. 

WORKS WITH ANY MACHINE . .,.$125.00 

TT-4A/TG ARMY TELETYPEWRITER. KSR, 60WPM. M5V/60CY. A GOOD MACHINE, TABLE 

TOP S12E PAGE PRINTER AND KEYBOARD , , . , $49.00 

PP^840/TRA-19 POWER SUPPLY , ,,,....,*.._ $16,50 



ORDER TODAY, OR REFER TO THIS ADVERTISEMENT DURING J 972. ALL EQUIPMENT 
EXCELLENT CONDITION F.O.B. ELLEN TON, FLORIDA SATISFACTION GUARANTEED OR 
MONEY REFUNDED! IMMEDIATE SHIPMENT: WRITE OR PHONE 813*722*1843, BILL SLEP. 




2412 HIGHWAY 301. NORTH, ELLEIMTON, FLORIDA 33532 



trt c r* "D 3J c w 



OOOH J.O 



^ 



THE DENSON ELECTRONICS CORP. 

203/875-5198 
POST OFFICE BOX 85 

ROCKVILLE CONN 06066 
WORLDS LARGEST SELECTION OF 

NEW &USED TV CAMERAS & ASSOC. EQUIPMENT 

Dear OM, 

If you were on our mailing list this past year, you probably received 
complimentary copies of our catalog and subsequent flyers wherein we 
offered outstanding values for the budget minded. 



971 A 1 



144 page Catalog chock full of bargains and television 
equipment from components to completed systems 

plus pages of technical information. 




th anniversary 



2nd EDITION 



972#1 



MADE FOR TELEVISION 



OMOF-A-KIND! 





mm SOUND MOVIES 



971 Dl 



Featured Ampex Printed Circuit Boards for Ampex 
cameras, VTR's, Process Amplifiers, etc, at bargain prices 



AMPEX 



971 D2 



Special Offer on new NORELCO VTR model EL3401 A/54 

Only $200. 




THE 



DENSON ELECTRONICS CORPORATION 

P. 0. Box 85 (Longview St.) 
Rockville, Connecticut 06066 

(203) 875-5198 



94 



73 MAGAZINE 



971 D3 



Only $24.50 for these background music 
FM Receivers & Audio Amplifiers. 





971 D4 



UNIVERSITY Sound 



#904 



Speakers, Trumpets & Drivers 




#90 



<P at bargain prices 



CONRAC 



971 





Special on Conrac 17" & 25" high resolution 
monitors. 




71 M3 




INDUSTRIAL TYPE MONITORS 
PROFESSIONAL TRANSISTORIZED VIDEO MONITOR at close-out prices 




71 





New Video Tape for helical scan recorders 1 " 1 hr. 

1/2" 1 hr. $24.95 $34.95. 

1/2" 3/4 hr. $19.95 

Plus bargains in zoom lenses, etc. 

Video Distribution Amplifiers for 5 channels - new 

Only $89.95. 




■rt 



All of those who are interested in amateur TV as well as commercial video systems should be on 
our mailing list. A copy of above flyers will be mailed free upon request until stock is 
exhausted. 

WAREHOUSE SALE May 6&7, 1972 - details flyer 972 #2 



THE DENSON ELECTRONICS CORPORATION 

P.O. Box 85 (Longview Street), Rockville, Conn. 06066 Tel (203) 875-5198 




IARCH 1972 



95 



COMPUTER 
GRADE 

ELECTROLYTIC 
CAPACITORS 

Mfd, by Sprague, Mallory & Sangamo 




MFD. 


Volt 


Size 


25,000 


6 


2x4- 


66,000 


6 


2-9/ 


40,000 


7 


2x5 


15,000 


10 


2x4- 


15,500 


10 


2x4- 


74,000 


10 


3-1/ 


15,000 


12 


2x4- 


11,500 


18 


2x4- 


2,300 


33 


2x4- 


3,500 


52,8 


2x4- 


3,500 


55 


2x4- 


6,000 


55 


2x4- 


3,100 


75 


2x4- 


3,750 


75 


2x4-' 


800 


99 


2x4- 


750 


1 65 


2x4- 


1,250 


175 


2x4- 


500 


200 


2x4-' 


300 


275 


2x4- 


250 


330 


2x4- 



/2 
6x4 

/8 

/8 
/8 



-3/4 



Price $.75 ea 



(ML FILLEDaA- CAPACITORS 



Mf d 
2 
4 

.25 

1 

.5 



Volt 
1000 
2500 
3000 
4000 
5000 




D 
1 

3-3/4 
1 -3/1 6 
2-1/4 
2-1/4 



PR I CE 

$1.25 

3.95 
2.35 
4.75 
2.95 



PLASTIC FILM CAPACITORS 

Glassmike ASG-503-2M. ,05 UF - 2000 
VDC. 3/4" DiA x 1-3/4. Axial stud 

Gudeman GC-246R202K* # 002 UF - 7500 
VDC. 3/4 M oiA x 2 M . Axial leads 

$.70 



AIR VARIABLE CAPACITOR 
Mfr. Hammarlund 



5 pf to 50 pr , 

SHAFT FOR THAT 
VFO ETC. 



GEAR REDUCTION ON 
FINE TUNING OF YOUR 



$.75 



TEST LEADS 



wmm 




ULTRA MINIATURE 2 GANG VARIABLE 

CAPACITOR 

Mfd* Monarch 

#CV-200. Maximum capacity, antenna- 

148.1 UUF. OSC I LLATOR-65.2 UUF. 

Trimmer capacitor effective variable 

CAPAC ITANCE-6 UUF. $,35 



WL* 




CB CASE & CHASSIS 

22 GAUGE STEEL CASES WITH SLIDE IN 

chassis. Originally made for CB 
radios. Front opening rolled for 
neater appearance. slotted vent- 
ILATION OPENINGS ON EACH SIOe(nOT 

shown). Size 3-3/4% x 8-3/4% x 
7 tr w. Panel opening 6-1/4" x 3" . 
May be had with or without mounting 

BRACKET, 

With bracket $3.25 

Without bracket $2.45 



COILED CORD (MICROPHONE) 
Mfr. Belden 







^8497. 3 conductor with 1 conductor 
shielded. awg stranding 23(21x36). 
0. D. 1/4". Extends from 11-1/2" to 
6'. Neoprene jacket. $.95 



UNETCHED PRINTED CIRCUIT BOARD 



Thi ck 

.0055 

.006 

.007 

.010 

.017 

1 /32 

1/8 

1/8 



Si ze 

8x8-1/2 
8x8-1/2 
10x14 

1 1 xi 6 

12x17 
8x10 
8x10 
8x10 



Copper 
Clad 

1 Side 

2 Side 
2 Side 
2 Side 
2 Side 
1 Side 

1 Side 

2 Side 



Pri ce 

$.32 EA 

.32 E A 

.80 EA 

.88 EA 

.99 EA 

.52 EA 

.95 EA 

$1 .10 EA 




TUNING METER 

Mfr. General Electric 
Type DW-33 

Dial calibrated in 7 divisions, white 
on black face. Meter reads tune for 
maximum. Movement - to 4.2 Ma. 
Built in socket for dial light. Flush 

MOUNT. 2-l/8" OIA. $.95 EA 



GERMANIUM DIODE: PRV 20, 



4 FT LONG, RED TEST PROD WIRE. WORK- 
ING voltage 10,000 Insulated banana 

PLUG ONE ENDj MUELLER TEST CLIP OTHER 

$.45 SEND FOR FREE CATALOG 

BRIGAR ELECTRONICS Minimum 

10 ALICE STREET &INGHAMTON, N Y. 13904 NO COD 



Fwd 50 Ma 

25/$ 1 .00 




turn onus 



607-723-3111 



Order 



$5.00 



mm 



BONUS SALE ! NEW LOW. LOW PRICES ! 

free 810 operational amplifier (dual) DIP w/data for all prepaid orders of $10. or more, 

, .; . . $1.25 value 

FREE 810 op-amp and one LM309K 5 volt 1 amp. power supply module (TO-3) with 

prepaid orders of $25. or more $3.75 value 

With prepaid orders for $50. or more you get the $25. bonus plus ten per cent discount 
on all items purchased. 




EPOXY TRANSISTORS 

Popular numbers, alt factory-marked with 2N-type 
numbers. Guaranteed minimum of 40 pieces of 
TO-5 and TO-18 mixed. Untested, but sampling 
indicates over 85% good. 

approximately 1 -ounce— 4(H transistors 

for only $1 .89 

DIGITAL SPECIAL 

Ten brand new (on carriers) dual-in-line JK flip- 
flops— LU 321 with data sheet and two pages of 
application notes describing hookups for— divide 
by three through ten, and twelve. Also self 
correcting ring counter hookups, etc. 

10 LU321 W/data $5.00 



TTL dual-in-line 
7400, 7401, 7402, 7404, 7405, 7410, 
7420,7430,7440, 

7450, 745 1, 7453 , ea.$. 30 

744 i BCD decoder driver . . 1 .40 

7442 BCD decoder , . . , . 1.40 

7473 dual JK flip-flop .... .... 65 

7474 dual type D FF . . . , . 50 

7475 quad latch ,1 .40 

7476 dual JK FF 65 

7480 gated full adder 80 

7483 4 bit full adder , 1.60 

7486 quad exclusive or gate . f -, : 65 

7489 64 bit RAM 4.00 

7490 decade counter 1 .40 

7491 8 bit shift register 1 .40 

7492 divide by 12 counter 1 .40 

7493 4 bit binary counter ... .,...,,...., 1 .40 
74154 one of 16 decoder . 3.00 

74192 up/down decade counter ............ 2.25 

74193 up/down binary counter 2.00 

741 95 iinv, 4 bit SR ■ 1 .40 

8220 parity gen/checker . , . , 1 .00 

8242 4 bit comparator 90 

8280 preset decade counter . . 1 .40 

8281 preset binary counter 1 .40 

8520 25 MC divide by "N" 

2 to 15 2.00 

7495 4 bit SHIFT REGISTER 1 .40 

8590 8 bit shift register 2.00 

8270 4 bit shift register 2.00 



LINEAR SPECIAL 

Ten (10) Teledyne TO-5 741 operational amplifiers 
with a two-page sheet of application notes covering 

the basic circuits using op-amps $.75 each 

Op-amp package 10-741's, data sheet and applica- 
tion notes only $7.00 



DIGITAL COUNTER MODULE 30MC 

unit includes board, SN7490, 
SN7475quad latch, SN 7447 
7 -segment driver and RCA 
"numitron" display tube 
W/decimal. 1" x 4.5" module 
wilt mount on 1" centers. 

kit $12 - wired and tested $15 



LED Red Emitting Lamp 60 

LINEAR IC's (dual-in-line) 

709 operational amplifier 50 

710 voltage comparator 75 

LM309K5V-1A 

power supply module ........ 2,50 

LM100 positive voltage reg * . . . .80 

747 dual 741 op amp DIP , 1.25 

LM302 voltage follower op-amp 1-25 



Ail IC's are new and fully tested — leads are plated 
with gold or solder. Orders for $5 or more will be 
shipped prepaid. Add 35rf handling and postage for 
smaller orders, California residents add sales tax. IC 
orders are shipped within two workdays of receipt 
of order — kits are shipped within ten days of 
receipt of order. Money back guarantee on all 
goods sold. 




ELfCTROHICS 




SEND FOR FREE FL YER 



P.O. Box 85 
CARMICHAEL, CA 95608 

(916)966-2111 





This is a sample listing of our stock. Some are one of a kind, many we have in stock in large 
quantity. We also have hundreds of others not listed. © 

All manuals listed are originals, not copies, and 99% are brand new, unused. 



ALA-2 


HSt 


6.00 


ABC-5T 


"HMt 


10.00 


ALR-5 


HSI 


9.00 


ARC-52 


HMI 


ro.oo 


ALR^B 


HSi 


13.00 


ARC-52 


IPS 


10.00 


APA-Ba 


HSI 


e.oo 


ARC-55 


HMI 


9.00 


APA-6 


HSI 


8,00 


ARC-94 


HMI 


9.00 


APA-11 


HSI 


7. SO 


ARC-119 


HMI 


9.00 


APA-16 


Hsr 


B.00 


ARC-120 


HMI 


9.00 


APA-17 


HSI 


9.00 


ARM-5 


HMI 


7,00 


APA-17a 


HSI 


9.00 


ARM-10 


HMI 


z^g 


APA-56 


HSI 


is.oo 


ARM-19 


^¥T^"^ 




APA-31 


HSI 


7 + 0O 


ARM^^ 




-#■% t 


APA-89 


HSI 


7.00 




k f*t 


1*1 lC^ 


APA-125 


IPB 


7._^L^^ 




t4C 


\ * x 


APG-30 


HSL- 






r\ Ki- 


APM-74 .—i 








^-t-rt 


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LM 17 
LM-18 
LP 3 



LR-1 
LR-2 



8.00 
10.00 

10.00 



TS-185d 



HMI 
HMI 
HMI 



HMI 



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AP 

AP 

AP 

APN 

APN 

APN- 

APN-V 

APrsl-1 

APG-2 

APR-1 

APR 2 

APR 4 

APR -5 

APR-6x 

APR -9 

APR-12 

APR-13 

APS2 

APS-3a 

APS -4 

APS-19a 

APS 20a,c 

APS-20e 

APS -31 + 

A PS -33+ 

APS -42b 

APS 44 

APS -45+ 

APSh88+ 

APT2 

APT-S 

APX-1 

APX 



AP 

AP 

AP, 

A OS 

ARA 

ARB 

ARC-. 

ARC? 

ARC-5 
ARC-5 
ARCM2 

RT58 
ARC-12 

(R-11) 
ARC-19 
ARC-27 
ARC-27 
ARC-28 
ARC-30 
ARC-3B 
ARC-38 
ARC-39 
ARC 48 



006 *rflttt CS 



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HMI 
HMI 
HMI 
HMI 
HMI 
HMI 
HMI 
HMI 



LOO 
20.00 
25.00 
25,00 
30.00 
40.00 
30.00 
3000 
7.00 



ONI** 



w-se 

ASA-13 

ASA-13 

ASB-3 

ASQ^S 

ASQ-10 

ASQ-17 

AT A/ ARA 

ATB 



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HMI 

HMI 

HSI 

IPB 

HMI 

HMI 

HMI 

HMI 



flPrtflS 



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i*v^ 



10.00 

9,00 

9.00 

19.00 

20,00 

7.50 

15.00 

15.00 

1 



itft* 



RDR 

RDR-1 

RDZ 

REJ 

RUQ 

SCR-269f 

SCR^274N 

SCR-718- 



10.00 

10,00 

8.00 

8.00 

12.00 

12,00 

7,50 

8.00 



HMI 



ttf*° 



■\tf# 



***** 




-M-44 
UPM-33b,c 

UPM-45 
UPM-46 
UPM 55, 

55a 
UPM-55, 

55a 
UPM-5 



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HMI 
HMI 
HMI 

HMI 
HMI 

HMI 



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iVces 



,pP e 



HMI 

HMI 

IPB 

HMI 

HMI 



7.00 

8.00 
10.00 
10.00 
10,00 
16.00 





P^^ 


-^ 8.00 


^^^ 


B 


9.00 


wf^ 


B 


8.00 


GP-67 1 


B 


8.50 


LAE-1 I 


B 


8,00 


LAF-2 I 


V 


8.00 


LM-2 I 


B 


8,00 


LM-7 I 


B 


8.00 


LM^13 I 


B 


8.00 


LM-14 1 


B 


10.00 


LM-16 I 


B 


10.00 



-10.11 
TCS-12 
TDB-2 
TDE-2 
TD2 
TED-3 
TRM-1 
TS-34a 
TS-47 
TS-1 47d 
TS-155C 
TS 186 
TS-186a 



HMI 
HMI 
HMI 



12.00 

12.00 

12.00 

12.00 

9 t 00 

8.50 

20.00 

8.50 

6,50 

9,50 

6.00 

8.00 

8.00 

8.00 

8.00 



M-80 
URM-129 
URM-t30 
URR-35 
URR-35c 
USM-3a 
USM-24C 
U5M-25 
USM-25 
USM-29 
USM-31 
USM-32 
USM-34 
US M-44, 

44a 
USM^105a 
USM-140b 
USM 141a 



HMI 
IPB 



soo 

8.00 
7.50 

9,00 
9.00 
6.50 
9.00 
7.S0 
8.00 
7.50 
7,00 
7.00 
7.00 
7.00 
7.00 
7.00 
6.50 

8.00 

.50 

(.00 

.50 

50 



7.50 
7.50 
7.50 
7.40 
9, GO 
7.50 

8.00 

8.00 

7.50 

t7,50 

10.00 

17.50 

6.50 

8,00 

6.50 

6.50 

8.00 

8.00 

8.00 

8.00 

5,00 

n.oo 
i .oo 

,00 
00 



9.00 
7.50 
7.50 
6.50 
6.50 
9.00 
9.00 
7.50 
9,00 
8.00 
8.00 
15.00 
7.50 
7.50 
7.50 

9.00 

10.00 
10,00 
10,00 



PRICES ARE AS LISTED FOR EACH MANUAL, WE PAY POSTAGE IF ORDER RECEIVED 
ALONG WITH YOUR CHECK. IF WE SHIP OPEN ACCOUNT POSTAGE WILL BE ADDED 
TO INVOICE VALUE. 

• WE STOCK EXCESS MILITARY MANUALS ONLY —NOTHING COVERING COMMERCIAL 
EQUIPMENT. 

• Write us about any needs that you may have* we rpight be able to supply just the manual you need 

ORDER TODAY - YOUR MANUAL MIGHT BE SOLD OUT TOMORROW! 

All publications are subject to prior sale without notice- 




C & H SALES CO. 

WELCOMES 1972 WITH AN OUTSTANDING SALE 

REAL DOWN TO EARTH PRICES. 



TEK 80 vertical plug tn less probe * . . . . $25,00 

TEK 80 vertical plug in with probe $35.00 

TEK TU2 test load plug in $35.00 

TEK 53B wide band calib. pre amp . . . . $65.00 
TEK 53D d iff. high gain calib. pre amp . $65.00 
TEK 53/54K fast rise calib, pre amp .... $65.00 
TEK "G" wide band diff. calib. pre amp $65,00 

TEK "N" sampling plug in 3100.00 

TEK "P" plug in test unit . . , . . , $25,00 

TEK "R" transistor rise time ........ $110.00 

TEK 121 wide band pre amp 5 CPS to 12 MC 

.. $25.00 

TEK 122 pre amp 0.2 Hz to 40 kHz . 1 . . $50.00 

TEK 105 sq. wave gen $50.00 

TEK 107 sq, wave gen $50.00 

TE K 160A power supply ............ $95.00 

TEK 161 pulse gen. . $65.00 

TEK 162 wave form gen $65.00 

TEK 163 pulse gen $65.00 

TEK 360 scope dc to 500 kHz $95.00 

TEK 190A constant amplitude sig. gen. .35 kHz 

- 50 MC ..... $95.00 

TEK 515 15 MHz scope $395.00 

HP. 151 high gain amp, $35.00 

H.P, 200 CDR audio osc. $125.00 

H.P. 201 B audio osc $35.00 

H.P, 202A function gen $75.00 

H.P. 210A sq. wave gen. $25.00 

H.P. 21 2A pulse gen $50.00 

H.P, 350D attenuator $50,00 

TS 403/U sig. gen. same as H.P, 614A 

1800-4000 MC $75.00 

TS 419 sig. gen. same as H.P, 61 4A 900-2100 

MC . $150.00 

H.P. 430C power meter ............. $35.00 

H.P, 41 7A VHP detector $150.00 

H.P, 608D srg. gen. 10-420 MC ...... $795.00 

H.P. 683C sweep osc. 2-4 KMC $150.00 

G.R. 107 'J" var. ind $25.00 

G.R, 107 "K" var. ind . $25.00 

G.R. 107 "L" var. ind . $25.00 

G.R. 107 "M" var. ind. $25.00 

G.R. 107 "N" var. ind $25.00 

G.R. 761 A vib. meter $75.00 

G.R. 1021 P2 sig. gen. with 1021^P1 P.3. 

250-920 MC $95.00 

G.R, 1203B unit P.S. . , $25.00 

G.R. 1208B unit osc. 65-500 MC $50.00 

G.R. 1214A unit osc, 400 or/1000C ....,„. $25,00 

G + R. 1218A osc. 900-2000 MC * 125.00 

G.R. 1264A P.S. $95.00 



G,R, 1401 A standard air cap. 1000JKF ±0.2% 

, $25.00 

G.R. 1401B standard air cap. 200 pF ±0.15% 

, $25.0U 

G.R. 14U9G standard cap. 0.002 JUF .... $17.50 
G.R. 1409K standard cap. 0.005 /iF .... $17.50 

G.R. 1432B standard ind $25.00 

G.R, 1482E standard ind $25.00 

G.R. 1482K standard ind $25,00 

G.R, 1482L standard ind. $2500 

G.R. 1490B decade ind $45.00 

G.R. 1490C decade ind $35.00 

G.R. 1570AL auto, volt reg $95.00 

Weston 310 ac~dc watt meter 0-75 watts $100.00 
Weston 338 single ph. power factor meter ,90 lag 

- .90 lead . $ 1 50.00 

Weston 341 V.M. 0-300 VAC * DC ... $75.00 

Gertsch PT5 ratio xmf r. . . . , $75.00 

Donner 2101 wave analyzer 0—50 kHz , $125.00 
Bruel & Kjoer 1012 BFO $350.00 

Sanborn 670A XY recorder --*•'•*•••#%• $300.00 
L&N standard res. \\l t 10i2, 1 0OiZ, 1000O, 

10,000J2 $35.00 ea. 

L&N K3 pot $150,00 

L&N 8662 port. M.V. thermocouple bridge — 

double slide wire . $75.00 

RFL 531 xtal. imp, meter 10 MC to 110 MC 

. $125.00 

FXR S772A osc. 1900-4000 MC $95.00 

FXR X772A osc. 7000-11000 MC .... $95.00 

PRD 650C power meter $75,00 

PRD 279 ratio meter $50.00 

Panoramic LF-7A tuning head 2-40 MC $195.00 
Panoramic SG-1 sweep gen. 40 CPS— 200 kHz 

,, . . . $150.00 

Sierra 158A H.F. wave analyzer with 2 probes. 

5-10 MC $150.00 

Microwave devices dummy load model 636NC 
5012 0-3000 MC 600 watts max. New. . . $75.00 

Rutherford B7 pulse gen $50,00 

Rutherford B7B pulse gen. $95,00 

A.R.C. 202F AM FM sig gen. 175-250 MC 

......$ 1 50.00 

Fluke 800 D.V.M $65.00 

Fluke 801 D.V.M. $75.00 



IF YOU DON'T SEE WHAT YOU NEED WRITE 
& ASK US. WE HAVE A VAST INVENTORY 
OF BEAUTIFUL LAB EQPT. WE ALSO SELL 
OPTICS. SEND US YOUR REQUIREMENTS. 



ALL MERCHANDISE IN EXCELLENT CONDITION 
SEND CHECK OR MONEY ORDER WITH ORDER 



MERCHANDISE SHIPPED FREIGHT COLLECT 
CALIFORNIA RESIDENTS ADD 5% SALES TAX 



C&H Sales 

2176 E. Colorado Blvd., Pasadena, California 91107 

213-681-4925 




GRAY 



ELECTRONICS 

SPECIALIZING IN USED TEST EQUIPMENT 

AH equipment FOB Monroe. 
Money back (/ess shipping) 
if not satisfied. 




Babcock BSR-7R uhfsig.gen .,400-420 MHz. . 
Beck man 1452 digital recorder, 6«digit, ...... 

Beckman 5500 counter-timer, 100 kHz, 

Boonton 160A Q mtr. 50 kHz-75 MHz 

Boonton 170A Q-mtr, 30-200 MHz„ ....... 

Dumont 303 tO MHz fast-rise trgrd. scope,. . . 

Dumont 304 A 300 kHz gen. pur, scope 

EGStG 707 Millimike 1 GHz g.p. Jab scope.. . . 
Epsco VR607B sec. voltage standard.. ....„*,. 

Gen, Microwave 550 WWV recvr/cornp 

GR650A Impedance Bridge, direct read RLC„ 

GR720A Freq. mtr., 10-3000 MHz.. s 

GR736A Wave Anal., 20 Hz- 16 kHz.. .,. 

GR1 100AP Freq, Standard complete w/3 units 

GR1101A Precision osc, for above 

GR 1 1 02A Multivibrator and ps for above,. 
GR1103A Synchronometer for above.. ....... 

GR1231B Null det. amp. w/P5 filter, ps.. 

GR1603A ZY bridge, 20 Hz-20 kHz , 

Gertsch FM-7 Freq. mtr., 20-1000 MHz,.0001% 

Hazeltine 1050B sig, gen. 900-1300 MHz 

HP175A 50 MHz scope, hi-gain dual trace ai 

delay plug-ins H755A-166B) 

HP200ABR audio osc., 20 Hz-40 kHz 

HP300A Wave Anal., 30 Hz-16 kHz.. 

HP330C Dist. anal., 20 Hz-20 kHz 

HP410A VTVM, to 700 MHz.. . , 

HP415B VSWR indicator/amp 

HP430C Microwave pwr. mtr . •■••#.« 

HP500BR Freq, mtr. 3 Hz-1 MHz., . 

HP524D Freq, counter, basic unit 10 Hz- 10 MHz 
HP525A Freq. conv., 10-100 MHz plug-in.. 
HP526A Video Amp., plug-in.. .......... 

HP526B Time Interval plug-in 

HP540B Trans. osc., 10 MHz- 12.4 GHz,. . , 

HP560A Digital recorder, 11 col 

Hickok 1822 scope plug-in (sim. Tek. B)„ , 
Hickok 1824 scope plug-in {Sim. Tek. D}.. . 
Hickok 1831 scope plug-in (sim. Tek. Kh. . 
Kay Mega-sweep Sweep Gen., 50 kHz- 1000 



z. 



Exceptional Value in Lab -Quality Frequency Counter. 
Universal counter-timer. Basic range is 10 Hz— 10 MHz. 
8-digit Nixie readout. Checks freq. period, etc. Similar to 
HP524C. 

• Unchecked and without time standard but complete 
with all tubes, Nixies, manual, etc.. $139. 

• Counter as above but with new solid-state time standard. 

1 7Q 

• Counter as above but with the time standard and 
completely checked out . . , . 209. 

• Any unit above with 1 plug*in range en tender (10—100 
or 100-220 MHz). . . , -add 49. 

• Any unit above with two plug-ins covering 10—220 MHz 

• Original 14-20C osc. and oven. Minor additional cir- 
cuitry required for power, instructions included 55. 



Kay Rada-sweep Sweep gen., 20—60 MHz ....... S1 15. 

Kay Rada-pulser 570A Sig. gen., 10-80 MHz 195. 

Kintel 301 DC standard/null voltmeter 220. 

Meas. 80 Stand, sig. gen., 2-400 MHz 225. 

Meas. 82 Stand, sig. gen., 20 Hz-50 MHz. . . 275. 

Nems-Clark 1671 FM rcvr 175-260 MHz, 210. 

NLS M-24 Digital voll-ohmmtr system, comp, , » . . , 585. 

NLS V-35 Digital voltmeter 465. 

NE 14-21C Freq conv. plug-in, 10-100 MHz. 65. 

NE 14-22C Freq conv. plug-in, 100-220 MHz 80. 

NE 14-24C Time Int plug-in. 45, 

Polarad R Microwave rcvr basic unit 285. 

Various R plug-in units available PUR 

Polarad TSA Spectrum anal, basic unit 325. 

Various TSA pJug-ins available PUR 



Polarad SA-84W Band switching Spectrum analyzer, 10 



GHz. 



MHz-44GHz , 

PRD 707 Broadband microwave osc,, 9—2.2 

PRD 907 Sweep Gen. 40-900 MHz 

RFL Xtal Imp. mtr. 800 kHz-15 MHz . . . 
Rollin 30 Stand, sig. gen. 40-400 MHz. . . 
Sens, Res. ESH Voltmtr., 0-20 kV. ..... 

Servoscope 1 100C Servo-system analyzer 

Tek 105 Square Wave gen 

Tek 1 T2 Direct-coupled amp. 20 MHz. 
Tek 51 7A Hi-speed sampling scope 1GHz. 

Military Nomenclature: 

FR 4U Freq mtr 100 kHz-20 MHz, .001% 

FR114U Freq counter 20 Hz-1 MHz, 6-digit Nixie 

ME 6D/U AC VTVM, .0005-500 V 

ME26D/U Mil. Vers. HP410B VTVM. 

RD142A Dual Chan, 24 hr. tape recorder, ...... 

TS147A/UP Sig. gen./Freq/Power mtr., 9 GHz. . . 

TS175C Freq, mtr. 85-1000 MHz, .01% 

TS403A Mil, vers. HP616 Gen. 1 .8-4 GH2, 

TS810/U Prec. ealib. 100 Hz, 1-10-100-1000 kH 
URM 25E Stand, sig. gen. 10 kHz-50 MHz. . . . 

URM 26A Stand, sig. gen. 3-410 MHz 

USM 16 Stand. Prec, sig. gen. 10-440 MHz, . . . 
USM 68 Microwave pwr mtr 450 MHz— 1 1 GHz. 
USM 105 Mil. vers, HP160B scope, dual trace, . 



1 ,260. 
170. 
125. 
320. 
585, 
.90. 
280. 
115. 
.95. 
345. 

.125 



135 
,35 

.85 
145 
.85 
.75 
385 
72 
215 
225 
675 
110 
550 



(Send SASE for complete list.) 



GRAY 






ELECTRONICS 

P.O. BOX 941 MONROE, MICHIGAN 48161 




Hank Olson W6GXN 

P. O, Box 339 

Men to Park CA 94025 







E-IR, or so Ohm's Law says, and we 
generally accept Herr Ohm's word for 

it. But there is a fairly large class of 
resistors for which Ohm's Law doesn't hold 
true; that is, for which a given voltage 
change does not cause a proportional cur- 
rent change. Such resistors are called non- 
linear resistors. 

ht What, resistors that don't obey E=1R? 
It sounds like an enemy plot to upset our 
electronics defense industry/' bellows the 
angry citrus county ham. Well, no; there's 
no plot; in fact, read on, old patriot. We'll 
see that nonlinear resistors are very useful 
to our electronics industry. 

In a minor way, nearly every resistor is a 
nonlinear one. That is, every resistor has 
some variation of resistance with tempera- 
ture. If current is passed through it, power 
(l 2 R) is dissipated in the resistor, , which 

changes the temperature of the resistor and 
thus its resistance. However, most resistors 
used in electronic circuits are designed to 
minimize resistance change with current, so 
that the assumption that each one has a 
constant resistance is a good approxima- 
tion. The newer metal-film resistors bring 
the concept of a noninductive, linear resis- 
tor very close to realization. 

The types of nonlinear resistors we'll be 
concerned with here are light bulbs, 
thermistors, Thyrite varistors, and similar 
devices. The light bulb is often called a 
barretter, a category which also includes 



small electrical fuses when used as circuit 
elements. 

Let's take the light bulb first, since it is 
the most familiar to most of us. If we plot 
a curve of voltage versus current as was 
done in Fig, 1 (for a small 120V Christmas 
tree lamp), one immediately can see the 
nonlinearity of the device. The E-I plot of 
Fig. 1 is typical for light bulbs, and several 
important facts can be observed about it. 
The light bulb has a positive resistance 
coefficient; that is, as current increases, the 
resistance increases. Also, one will notice 
that (for normal temperature environ- 
ments, where humans and electronics oper- 
ate together) the greatest nonlinearity 
occurs at only a few percent of the normal 
operating voltage of the lamp. 

Several other facts can be learned by 
more careful measurement. First, the lamp 



16 
14 




























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' 








— 




























uj 






















































4 
2 















Ch 


(RISTMAS TREE LAMP 


















* JAPAN 12 GV" 





























& 10 12 14 16 IS 20 22 24 

I <mA) 



Fig. I", A curve showing voltage versus current in 
a small 120V Christmas tree bulb. 



MARCH 1972 



101 




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Depend on . . . 

We can supply crystals 
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Over 6 million crystals in 
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DIRECT with check or 
money order to JAN 
CRYSTALS. For first class 
mail add 150 per crystal 
—for airmail, add 200 per 
crystal. Inquire about 
I special quantity prices. 

Color 



DIVISION OF BOB 

WHAN & SON 
ELECTRONICS. INC. 

2400 Crystal Dr. 

Fort Myers 

Florida 33901 

(813) 930-2397 

Send 10C for new 

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and lists of 

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stock. 



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1000 KHz frequency standard (HC 6/U) 
Any CB crystal, trans, or rec. 

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Any amateur band crystal in FT-243 holders 

(except 80 — 160 meters) 

4 for 
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o *Ecc 



OUTPUT 



Fig, 2. The light bulb as a nonlinear amplifier as 
used in the Wien bridge oscillator. 

lus a time constant: that is, it will follow 
only slow changes in current. For our 
120V bulb of Fig. I, this time constant is 
of the order of one-half second. Secondly, 
at any point on the curve, if we shine a 
second incandescent lamp (operating at its 
nominal 120V) directly on the lamp under 
measurement, the measured current will 
decrease. 

Perhaps the best known application of 
the light bulb as a nonlinear resistor is its 
use in the popular Wien bridge audio 
oscillator, as shown in Fig. 2. The left side 
of the bridge provides positive feedback to 
the gate of Ql, allowing oscillation to 
occur around this two-stage circuit. The 
right side of the bridge provides negative 
feedback to keep the amplitude of oscil- 
lation constant. 

If the audio oscillator is initially operat- 
ing satisfactorily (in class A), a change of 
operating conditions which increases out* 






OUTPUT 




Fig. 3, A lamp as a stabilizer in the Meacham 
bridge crystal oscillator, 

put will increase the audio voltage across 
R3 and r. The increase in voltage across r 
increases the resistance of this nonlinear 
resistor, which decreases the gain of the Ql 
stage, restoring our original operating con- 
dition, 

There is one consideration in Wien 
bridge design, however, that sometimes 



102 



73 MAGAZINE 



isn't appreciated: The time constant of r 
must by large compared to the period of 
the lowest frequency of oscillation, This is 
necessary so that the resistance of r is only 
dependent on the rms value of output 
voltage, and does not vary at the audio 



-24 V 



2N235A 




SPEAKER 



+ 24V 



Fig. 4. Two lamps in a pseudo-complementary 
output stage. 

frequency rate. Bulb time constant can be 
a problem at 10 Hz ? the lower range of 
some audio oscillators; this is one of the 
reasons that (large) 120V 6W bulbs are 
used in many audio oscillators, 

Another oscillator which uses a lamp as 
a stabilization device is the Meacham 
bridge crystal oscillator. The elementary 
form of the Meacham bridge is shown in 
Fig, 3. Since this oscillator is a narrowband 
device, transformers can be used for match- 
ing and phase inversion. 

The bridge is balanced when the point- 
to-point ac voltage is zero. In perfect 
balance, the Meacham bridge will not 
oscillate. But when a slight unbalance is 
present, typically 1%, oscillation occurs. 
The lamp is positioned in the bridge in 
such a way that an increase in its resistance 
will adjust the bridge toward balance. 

The best choice of bridge values occurs 
when R=Ri = Ri^Ra. Since R (the series 
resistance of the crystal) is determined by 
the crystal supplier, we have very little 
control of this parameter. Starting with R, 
we must then find a lamp which offers the 
same resistance (R ] ). The resistance Rj 

must equal R at a point on the E-I curve of 
the lamp where resistance is changing 
rapidly and this value of E x I should also 
be approximately the value of power we 



expect to dissipate in the crystal in opera- 
tion. 

Since, in the previous two examples, the 
light bulb was used as a measuring device 
(measuring rms voltage or current), why 
couldn't it be used as an rf monitor? 
Lamps can be used as barretter elements at 
frequencies where their inductance is small 
compared to their resistance, The resis- 
tance of the element is then measured with 
an audio frequency bridge, the rf circuit 
(including the barretter leg) being de- 
coupled by rf chokes and capacitors. 

Because of the "loop" construction of 
most lamps, the inductance of a lamp is a 
severe limitation on usefulness at higher 
frequencies. The instrument fuse, however, 
because of its size and axial construction, is 
much more easily used as a barretter 
element. The 3AG or SAG fuse is easily 
placed in a coaxial system for measurement 
of power. For years, standard 1/200 amp 
and 1/1 00 amp Littlefuses have served as 
barretter elements in power measurements 
up to 4000 MHz. 





















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Fig. 5. A selection of El plots (continued on the 
following page). 



MARCH 1972 



103 



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104 



Fig. 5. A selection of E4 plots (com.) 



73 MAGAZINE 



So far, we have seen lamps used as 
stabilizing elements in oscillators and as 
elements in bolometers for power measure- 
ment. A similar use of lamps is in the 
application of current limiters or fuses. In 
many circuits which may be subject to 
expensive failures, lamps may be used to 
slow down destructive runaway currents, 
and then "open," fuse-like, if the runaway 
continues uncontrolled. One such applica- 
tion is in push-pull or pseudo-push-pull 
transistor output amplifiers; Fig. 4 shows 
two lamps in a pseudo-complementary 
output stage. In this particular design, 
separate positive and negative supplies are 
used, and the speaker is direct-coupled. In 
case of a failure of one output transistor, 
the speaker is protected, as one of the 
bulbs will open in about 0.1 second. 

In order to be able to use lamps as 
nonlinear circuit elements, one must know, 
in fair detail, their E-I characteristics. E-I 
plots on common lamps are not generally 

available, and so must be plotted by the 
user. A selection of E-I plots is presented in 
Fig. 5, as measured by the author. The 
curves in Fig. 5a through 5j all show 
somewhat similar shape. The fact that 
some seem to display a sharper "break" in 
slope is apparently due to details in the 
form and mounting of the lamp filament. 

A (rare?) exception to normal lamp 
behavior was found in one old telephone- 
style bulb. The E-I plot of this unit is 
shown in Fig. 6. This unit is apparently an 
old carbon filament type, and its response 
came as quite a surprise. 

The curves presented in Figs. 5 and 6 
should be taken as "typical" for their 
particular types; individual units can vary 
somewhat. 

The second nonlinear resistor that we 
shall examine is the thermistor, a device 
not so familiar to most hams as the light 
bulb. Actually, there are many thermistors 
in use by hundreds of amateurs across the 
country, but they probably don't think of 
them as such. The thermistors generally 
used by hams are those which were 
designed for TV sets with series heater 
strings, but which are used in high power 
final amplifiers as plate parasitic suppres- 




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UI lieu TWX: 810-459-1970 




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For use in; Smalt or ders accept ed Crystal prJ£es @ m % 

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FM Schematic Digest 

A COLLECTION OF 

MOTOROLA SCHEMATICS 
Alignment, Crystal, and Technical Notes 

covering 1947-1960 
136 pages 11 1 / 2 " x 17" ppd $6.50 

S. Wolf 

11 00 Tremont Street 

Boston, Massachusetts 021 20 



MARCH 1972 



105 





'// 



CX-7A 



New "A" model Now Available 
Still $2195 - Great New Reliability 




Phone/write Don Payne, K4ID 
For a brochure or big trade-in on your gear 

PAYNE RADIO 

Box 525 Springfield, Tennessee 

days (615J384-5573* nights (615)384-5643 



EVICES 



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HALID-1 REPEATER 

IDENTIFIER 




■ 



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K-ENTERPRISES 



14Q1 NORTH TUCKER SHAWNEE. OK 74801 



20 



IS 



O 



10 




20 



40 60 

I (mA> 



SO 



100 



Fig. 6. The E-I plot of an old telephone style 
bulb. 



sors. The General Cement Glo-bar type 
25-912 is typical for this use, having a 
resistance of 20O hot and 250£2 cold. The 
variation of resistance with temperature 
(not with dc, since there is a coD in parallel 
in parasitic suppressor service) makes little 
difference in this application. 

Thermistors — that is, thermally sensi- 
tive resistors — are made of metallic oxides 
of manganese, cobalt, and nickel which 
have been sintered at high temperature. 
They are ceramic-like in their physical 
characteristics, and they are very stable 
electrically. If one uses a thermistor with 
very small current passing through it (not 
enough current to dissipate a significant 
amount of power in the device) we find 
that it has a temperature versus resistance 
plot like that in Fig. 7. From this plot, the 
obvious use for a thermistor is in the 
measurement of temperature; and many 

are used for that purpose. The thermistor 
once calibrated, measures temperature by 
itself; unlike the thermocouple, which 
needs a temperature reference. 



10 OO 

TOO 
500 

900 

200 



a 
§ 






100 
70 
50 

30 
20 

10 

7 
5 

2 













■ 








r 1 


























I 






















































i 




























N v 














1 






















































































































^l^ 









































ZQ 40 



60 



BO 100 120 140 160 150 200 
TEMPERATURE *C 

Fig, 7, The temperature versus resistance plot of 
a thermistor* 



106 



73MAGAZfNE 



Temperature compensation is another 
use for thermistors. This can be as simple 
as using a low resistance thermistor in 
series with a relay coil to prevent its 
drawing too much coil current when very 
cold. An example of temperature compen- 
sation of a phase shift oscillator is shown in 
Fig. 8, Of course, the oscillator in Fig, 8 
could also have been frequency- 
compensated with negative-temperature- 
coefficient ceramic capacitors. 

If larger currents are used in the 
thermistor, so that power is dissipated in it 
faster than heat can be conducted or 
radiated away, a different situation exists. 
In this case an E-I plot similar to Fig. 9 
applies. To the right of Vm, in Fig, 9, the 
thermistor has a negative resistance coef- 
ficient, due to the heating effect of cur- 
rent. In this negative slope region, ther- 
mistors may be used in circuits as nonlinear 
resistors having the opposite slope as 
lamps. 



♦ 15 



33k 



56yf 



l2Q0pt iZOGpf \200p1 

-)l T ) l T ) \~ 



IS* 



13k 








Fig. 8, Temperature compensation of a phase 
shift oscillator. 

In Fig. 2, if R3 is made a thermistor and 
r is replaced by a common resistor, the 
Wien bridge oscillator can be made to work 
just as well as originally. Since thermistors 
which are generally available have time 
constants of one second up to several 
minutes, the requirement that the non- 
linear element in the Wien bridge respond 
only to the rms value of audio oscillation is 
easily met. 

The Meacham bridge crystal oscillator 
(Fig. 3) is also operable using a thermistor 
in the lamp leg of the bridge (Ri ), if one 
also reverses the sense of either transformer 
in the circuit. 

Like lamps and fuses, thermistors are 
used as barretters for the bolometer 



method of measurement of radio fre- 
quency power. The thermistors used are 
very tiny, so have little inductance and fit 
conveniently into transmission lines. 

Vacuum tubes have heaters or filaments 
that behave similarly to lamps as to their 
E-I characteristics. That is, until a tube 
heater or filament comes up to a visable 
red or orange color, its resistance may be 
only a fraction of its nominal value. This 
means that when we plug in our tube-type 
receiver, the initial current drawn from the 
line may be several times the normal 
operating value. Since the thermistor has the 
opposite (E-I) coefficient to the tube, one 
is often put in series with the line to limit 
initial inrush current. This is especially true 
in series-heater TV sets, where the pre- 
viously mentioned General Cement 25-912 
is used. Not only is inrush current limited 
by such a thermistor; but since the tubes 
warm up much more slowly, the tube 
heaters are subjected to far less thermal 
stress, resulting in better tube life. 

Thermistors are not special or rare 
devices; being made by GE, Veco, Fenwal, 
Ferroxcube, and others. Several manufac- 
turers' types of thermistors are obtainable 
from Allied Radio's mail order service, 
making them available easily anywhere in 
the U.S. 

The last type of nonlinear resistor we 
will cover is the Thyrite varistor. This 
element is rather an old one as electronic 
devices go, having been introduced about 
1930. The Thyrite varistor was first devel- 
oped for use as a lightning arrestor, and is a 
relative of the coherer - that ancient 
detector of waves in the ether. 



12 



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0.5 



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CURRENT (AMPERES} 



2 



2£ 



Fig. 9. The E-I plot of a thermistor using larger 
currents so the power is dissipated faster than 
heat can be conducted away. 



MARCH 1972 



107 



70 



60 



90 
•40 



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lif 



20 
10 



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THYRI1 

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12 



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350 



300 



taf 



<50 



NOMIkAL ORPT 



G£ THYRlTE^VARISTOR 
250V0C 

i Vfl INCH DIAMETER, 
T/« INCH THICK 



E 


l 


(VOLTS 


(mA) 


10 


0,004 


20 


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30 


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40 


0.03O4 


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60 


069 


70 


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150 


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200 


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Fig. 10. The E-I phi of a Thyrite varistor, 

Thyrite displays a negative coefficient 
of resistance versus voltage, like a ther- 
mistor, but differs in a very important way. 
The resistance value of the Thyrite varistor 
does not take seconds or minutes to be 
established, after application of voltage. 
This means that the Thyrite varistor fills 
the need for a "fast" limiter, one which 
will respond at the ac rate. This fast 
response shouldn't come as any surprise, 
since the stuff was designed for lightning! 

Figure 10a shows an E-I plot of a 
representative Thyrite varistor, and Fig. 
I Ob shows another higher-voltage type. 
Both curves show identical curvature even 
though the plots have quite different 
scales. This agreement is due to the fact 
that Thyrite follows the relation i=Ae 3 ' 54 - 
What this means, simply, is that if one 
doubles the voltage across any piece of 
Thyrite, the current through it will increase 
roughly twelve times. 

Thyrite is useful any place we wish to 
attenuate transient voltage spikes, whether 
they come from the ac Line or are inter- 
nally generated by circuit components. For 



example, Thyrite varistors are widely used 
across relay coils to control the inductive 
spike that occurs when the relay is deener- 
gized. 

Figure 1 1 shows a simple power supply 
that uses three of the Thyrite varistors of 
Fig. I Oa to protect the rectifiers. The two 
varistors across the transformer secondary 
are to protect against transients that are 
coupled from the ac line. The third varistor 
is to damp the inductive spike which 
occurs when the supply is turned off and 
the choke field collapses. These particular 
Thyrite varistors have been used exten- 
sively by the author because of their 
convenient size, voltage rating, and low 
price, They are available for 49 cents from 
Red Johnson Electronics, 3311 Park 
Boulevard, Palo Alto, California (who also 
sells the 1 6 VA transformer shown in Fig. 
11 for $1.89). The fully protected supply 
can thus be built for about $10. 




TRfAD 
SPECIAL 



IJ7VAC 
LINE 



! 




Fig* 11. A simple power supply using three 
Thyrite varistors to protect the rectifiers. 

Like thermistors, Thyrite varistors are 
available through the Allied catalog and so 
can't really be considered odd devices. 
Although Thyrite varistors are historically 
old devices and are somewhat bulky, their 
use costs little and can save many dollars 
worth of expensive semiconductors, 

Bibliography 

L Olson, H. "The Wien Bridge Oscillator," 73 
Magazine 1967. 

2. Terman, F., and Petti t v JL, Electronic Measure- 
ments, McGraw-Hill, 1952, p. 45. 

3. Victory Engineering Corp., "Handbook of 
Thermistor Applications," 1963. 

4. General Electric, 'Thermistor Manual," 1956. 

5. McEaehron, "Thyrite: A New Material for 
Lightning Arresters/ 1 General Electric Review; 
Vol. 33, No, 2, Feb. 1930. 

. . , W6GXN ■ 



108 



73 MAGAZINE 



CIRCUITS, CIRCUITS, CIRCUITS. 

The following circuits have appeared in the referenced books, magazines, application notes, etc. 
While we try to reproduce all of the information that should be needed by an experienced constructor, 
readers may want to avail themselves of the original sources for peace of mind. 

Readers are requested to pass along any interesting circuits that they discover in sources other than 
U.S. ham magazines. Circuits should be oriented toward amateur radio and experimentation rather 
than industrial or computer technology. Submit circuit with all parts values on it, a very brief 
explanation of the circuit and any additional parts information required, give the source and a note of 
permission to reprint from the copyright holder, if any, and the reward for a published circuit will be a 
choice of a 73 book. Send your circuits to 73 Circuits Page, 73 Magazine, Peterborough NH 03458. 



TO J 90 ft 
PLATE RES 



TO REGENERATION 
CONTROL 




R3 

-V\Ar 



3 3K 







ei 



5-meter for the "Sixer, "' from 73, July, 1961, 
designed by K5VMC. The circuit is applicable to 
the "Tenner" and "Twoer" as well. It consists of 
an inexpensive 0—1 mA meter and a single tran- 
sistor meter amplifier. Half -scale deflection is 
obtained on a signal strong enough to quiet the 
background hiss as compared to about 114- to 
1/3-scale on a 20 f Q00 ohms per volt meter or a 
VTVM reading the voltage drop across the plate 
dropping resistor, 



IN34A 




PICKUP LOOP 
NO. 14 AWG WIRE 
2 in, LONG 
1/2 in, SPACING 



:.ooi 



+ i 



90 



RF Sniffer designed by W5JCB f from an article by 
KSJKXin 73 Magazine, December, I960, 



+ft voc 




«A 



0.1 U? 



Motorola MFC6QQ0 monolithic functional circuit, 
in an audio amplifier application. Circuit courtesy 
of Motorola Functional Circuits catalog. 




*46 98 MHz 
3rd OVERTONE 



Crystal oscillator for aligning receivers, reprinted 
from FM Magazine in FM Anthology I, available 
from 73 Magazine for $3.00. 



no 

VAC 




(OPTIONAL) 



Tl - FILAMENT TRANSFORMER 
£4 VAC, Z AMP 



01 THRU 05 - 50V FIV, I AMP 



Power supply for 0—20 volts up to I A, Run that tape recorder, transistor radio, pre-amplifier, or 
charge a battery. Circuit courtesy Calectro Handbook (50<t), 400 S t Wyman, Rockford IL 61101. 






MARCH 1972 



109 



12 VDC 



CERAMIC rv \C 

mikeUH 1\ 




TO 
DEVICE 



D2 

HEP 300 



RESET 
SWITCH 
(NORMALLY 
CLOSED) 



ALL RESISTORS- I/2W 



Sound activated relay. Control any circuit with a clap of the hands or any sharp sound. The circuit 
remains activated until manually reset It has adjustable selectivity. Circuit courtesy Motorola HMA-33 
"Tips on Using FET's." 



-o o 



£10 



IK 
-wv- 



IlOOO ^F 

N25V 




Timing switch, 10 to 100 seconds. No off switch 
needed since circuit draws only 1 yj\ when not 
used. Great for darkroom, 10 minute timer for 
identification, repeater shutdown for windy talk- 
ers, etc. Ql is a Calectro K4-506 transistor. Circuit 
courtesy Caiectro Handbook. 



12 VDC 



TOUCH 
PLATE 




/77 



Rl 

10 MEG 



ALL RESISTORS- 1/2 W 



Touch switch. This switch is operated by body 
capacity ... just touch the plate to operate the 
relay, How about this to turn the rig on and off? 
You can use a latching relay f time delay relay, 
stepping relay, to do just about anything. Circuit 
courtesy Motorola HMA-33 Tips on using FETs, 
available free from Motorola, Department 73, Box 
20924, Phoenix AZ 85034. 



-I0VO 



INPUT/Ts 
LO-Z® 



GNOO 




This singJe-tone decoder has a high degree of 

selectivity, stabiiity and reliability. Designed by 
Bob Mueller K6ASK, it and its companion encoder 
beJow appeared in FM Magazine in January, 1 968. 
The article is reprinted in FM Anthology I, 
published by 73 Magazine, 



-f20 



GNDO 




JLI 
5l05mH 



KEY 



m 

LEVEL 
ADJUST 



@ OUTPUT 



K6ASK single tone encoder (see above). 



110 



73 MAGAZINE 



HEP 602 



CRYSTAL 
MIKE 



22K 




iF8 
VDC 



O-*^ 



LI-FERRITE ANTENNA COIL (VARIABLE} 
L2-(5#t Text) 



AM wireless transmitter. Useful for baby-sitting, 
sick watch, intercom, and plenty etc. Circuit 
courtesy Calectro Handbook. LI is a variable 
antenna coil, fertile, Calectro D 1-841. L2 is four 
turns of hookup wire wound on top of LI. Q2-3 
are NPN silicon transistors Calectro K4-507. 



,002 
3KV 




CKJTPLT 



rlf-® 



fT7 



RFC2 



sen in m 

■f 100 TO+SX* 6 VAC 



4CX250 amplifier for six and two meters, using 
single pole switching. By K1CLL, from 73 Maga- 
zine, April, 1966- Simple modifications by Fritz 
Hervey K4ETZ [forget the 6 meter coil and use 
smaller PA tuning capacitors, Class C bias and a 
grid tank) allow 1QW drive, 200-250W out with 
enough air on the anode. Amplifier should have a 
screen clamp tube with G2 supply bled down from 
high B+ for best results, says Fritz . . . and he 
suggests a TV power transformer with a doubler 
for cheap 1,2— L 5 KV power. 



S2A 




r 



. DSI 

CD) 12 VOC 
LAMP 






Car radio converter, by WA8ALL, from FM Magazine, June 1967, reprinted in 73 's FM Anthology I. 
There's no text or anything with the original, either. . .just the circuit. 



MARCH 1972 



111 



IV 



REPEATER 
BULLETIN 






As a reader of 73 you may be interested in 
the newest FM bulletin . . . the Repeater Bullet- 
in* This magazine is published by 73 Magazine 
just for the users of repeaters, particularly in 
the New England and Eastern New York areas 
and it carries news of activities of the repeaters 
covering this section of the country. 

In addition to news from the repeater clubs 
the Repeater Bulletin will carry maps showing 
the coverage of the repeaters, discussions of the 
problems faced by repeater groups . . , discus- 
sions of frequency coordination, of functions 
being added to repeaters, of whistle-on, of tone 
burst, of touchtone, and continuous tone 
coding and decoding . . „ antennas . . . coverage 
of repeaters . . . hints for mobile installa- 
tions . . * cross-band links . . . circuits of value 
to both users and repeater owners ... a biblio 
graphy of the articles being published on 
FM . . . discussions of new equipment being 
brought out ■ , B ideas for repeater develop- 
ment . . . new frequencies . B . 220 plans and de- 
velopments . , . 450 repeaters and their prob- 
lems . . . problems faced by FMers in other 
areas of the country worthy of consideration in 
the North East . m . news of club meetings . . . 
symposiums . .. conventions ... dinners .. . 
auctions . . . swapfests . . , and other social 
events . . .etc. 

The Repeater Bulletin is available absolutely 
FREE to every repeater user in the New 
England and Eastern New York areas ... just 
send in an application form for qualification 
indicating that you are an active user of FM. If 
you live outside of this area (if you are unable 
to use any New England repeater), the Repeater 
Bulletin is still available, but at a subscription 
price of S2 per year. 

If the Repeater Bulletin is successful, it is 
always possible that its coverage may be ex* 
tended to cover more of the country or that 
other regional editions could be published. We 
have alt of the facilities here at 73 to turn out 
publications such as this quite economically, so 
we may be able to provide a communication 
medium if it is needed in other areas. 

The Bulletin is in a large format \BW* x 1 1 M ) 
and runs 24 or so pages per month. 



Repeater Bulletin Subscription Order Form 

Q I am actively using a New England Repeater 
and wish a FREE subscription. 

)S2 is enclosed for a one year subscription to 
the Repeater Bulletin. 



N ame 



Call 



Class License 
Address 



City 



State 



Zip 



REPEATER BULLETIN PETERBOROUGH NH 03458 



CRYSTAL 



HEP 802 

D l0K 




LI- 4 TURNS 16 OR 18 AWG WIRE (5e* Ttit) 




FM wireless transmitter (88—108 MHz), Might be 
used for bugging a room or something like that 
Circuit courtesy Calectro Handbook, C7 is a short 
length of twisted hook up wire about 1/2 inch 
long. LI is four turns length about 1/2 inch and 
1/4 inch dia. Carefui with this one, it can cover a 
iot of territory l 



S VDC 

+ 



INPUT O 




TPUT 



LI - 3-1/4 TURNS, TAPPED AT 1-1/4 TURNS, 

NO 26 AWG WIRE 
L2- 9-1/2 TURNS, NO 34 AWG WIRE 
L3- 5 TURNS. NO. 26 AWG WIRE, 
L4- 1-1/4 TURNS, NO, 26 AWG WIRE, AT LOW 

END OF L3. 

AUL RESISTORS- l/ZW. 

ALL CAPACITORS- IOV. 

NOTE: ALL LEADS SHOULD BE KEPT AS SHORT AS 
POSSIBLE fPC 90ARD 15 RECOMMENDED) 



Two meter preamplifier. Very few receivers will 
not be improved with a preamplifier such as this. 
The coils are wound on Miller ^QAOZZA forms, 
or any other smalt brass slug ceramic forms. A PC 
board is recommended. Circuit courtesy Motorola 
HMA-33, Tips on using FETs. 



112 



73 MAGAZINE 



Neil Johnson W2QL U 
74 Pine Tree Lane 
Tappan NY 10983 



SIMPLE 




CONTROLLER 



Some time ago I had a problem with 
the night light in my entrance hall. 
The little bulb kept burning out. The next 
step was to install a larger bulb. This was 
not too bright. About this time, I pulled 
the Variac from the workbench and deter- 
mined what constituted a satisfactory set- 
up. But it seemed foolish to keep a 1 kW 
Variac tied up in controlling less than 1 OW 
of power. The simple circuitry used in the 
solution to the problem should appeal to 
the reader, not only for light control, but 
for many other ac-dc applications. Light 
control, soldering iron heat control, and 
speed control for small universal ac-dc 
motors are but a few examples. 

Most experimenters are acquainted with 
the fact that with a small current load, the 
dc output of a capacitor-input type of 
filter will soar to relatively high voltages, 
Advantage is taken of this fact in the 
simple circuit under discussion. The circuit, 
shown in Fig. 1 , has only seven parts: three 
capacitors, three inexpensive slide switches, 
and a silicon rectifier. Cost for the whole 
thing? Three or four dollars, if you buy all 
new parts. 




400 PIV 

— W— 



2A 

CIRCUIT 
BREAKER 



enF 







30 MF i 



DC OUT 



Fig, 1, Schematic diagram. 



A diode will rectify the ac at 120V and 
convert it to pulsating dc. Due to a small 
loss through the silicon rectifier, the out- 
put voltage will come out close to half of 
what is fed into it. If the ac is 1 20V, the 
pulsating dc will be close to 60V. When 
read on a dc voltmeter, the true DC voltage 
will be roughly 54V(60Vdueto half- wave 
rectification x 0.9). If this voltage is then 
applied to an incandescent lamp, the actual 
input wattage will be approximately 
25% - that is, half voltage at half current. I 
say "roughly 25%" since my calculations 
have been simplified and do not include 






MARCH 1972 



113 



E peok 






A 

E 0c =2.9V 
(53V IF 120 VAC IN) 



a 

{eO VDC IF l£0 VAC IN) 



E[>c^.ev 

(86V IF 120 VAC IN) 





1/60 SECOND 



D 



BASELINE 



E oc -6.4V 
(H9 VDC1F 120 VAC IN) 



E 
E DC = B.9V 
(160 VDC IF 120 VAC IN) 



Fig. 2. NOTE: These waveforms and dc voltages shown are for purposes of illustration only. The 
actual dc output voltage from the unit diagrammed is much higher, running from a minimum of 53V 
to a theoretical maximum of 168V dc when fed with 120V. These CRO pix illustrate how a 

condenser-input type of filter wilt give more "boost" with varying amounts of capacity when feeding a 
fixed load. 



the resistance-vs-temperature factor of the 
tungsten filament. If we introduce a small 
capacitor at the input to the filter, this will 
boost the pulsating dc output voltage 
slightly. The actual voltage will depend 
principally upon the size of the filter 
capacitor and the current requirements of 
the load being supplied. Through the appli- 
cation of three capacitors of 8, 16, and 30 
fiF, we can obtain eight discrete steps 
throughout the range of the controller. 
That is, we can use the output of the 
sUicon rectifier with 0-8-16-24-38-46 
or 54 fiF of input capacity. This will give a 
wide range of control for small loads, any 
nonreactive type of load, up to a maximum 
of SOW with the normal line voltage of 
120V ac being fed into the input. Strictly 
ac types of electrical equipment, such as a 
transformer, cannot be fed from the con* 
trailer, since the output voltage is pulsating 
dc. 

A look at the oscilloscope will show 
how this variation in voltage is effected. In 
Fig. 2 the unaltered half-wave of the 
rectified and unfiltered dc shows above the 
baseline. As more capacitance is added 
across the rectifier output, the valleys 



between the alternate pulsations of dc start 
to fill in. A close examination of the last 
CRO presentation will reveal that the 
rectified dc pulse does not return to the 
baseline, where it would touch zero. In- 
stead it remains at a much higher average 
level, due to the storage effect of the 
capacitors. 

With a 120V ac input, this would 
amount to 1 69V. For this reason, it is 
always wise to start the controller with 
zero capacity, and then add small incre- 
ments of capacity. When the characteristics 
of a particular load become familiar, the 
controller may be turned on to a pre- 
determined setting. 

My main use for this simple controller is 
the setting up of certain light intensities, 
plus heat control for a small soldering iron. 
There are no theoretical limits for a device 
of this nature, but economic realities limit 
its function to controlling powers up to 
SOW, Beyond that range, other devices 
begin to come into their own. However, 
the simple diode controller does a very 
effective job up to SOW or so, and does so 
with low cost and simplicity. 

. . W20LU" 



114 



73 MAGAZINE 



H, P. Fischer VE3GSP 
1379 Forest Glade Road 
OakviHe, Ontario 



Some Harmonic-Suppression 

with a Low-Pass Filter 



or 



How to Eliminate THE Major Source of TV! 



VI is predominantly caused by radi- 
ated harmonics. Particularly the 14, 
21, and 28 MHz bands cause harmonics 
that fall into TV channels 2—6. This was 
my problem also and it was fairly easy to 
cure it, 

I was stuck with TV I a long time 
because most literature listed several sour- 
ces of TVI and I was not able to classify 
my source. As for remedy, I didn't want to 
spend any money on a trial-and^error basis. 
But eventually, it became obvious that the 
problems were antenna-radiated harmonics, 
and that the cure would be a low-pass 
filter- 
To make triple-sure, I borrowed a grid- 
dipper and fiddled myself a standard pick- 
up coil, which I hooked up to my dummy 



TRANSMITTER 



COAX 



REFLECT. 



COAX 



LOW- PASS 
FILTER 



TO ANT. 

OR 
TUNER 



Fig. h Diagram of filter set-up. 



load. Then I tuned the spectrum while f 
switched to 10, 15, and 20m bands. And 
there they were — harmonics, 57 MHz, 63 
MHz, 85.5 MHz. And when I checked the 
TV channel frequencies, I really under- 
stood why I had to have TVL I estimated 
the power level of my harmonics by 
switching my pickup coil over to a little 
transistor oscillator, on 27 MHz, which 
puts out 30 mW, rf. This indicated that my 
harmonics at 57 MHz were 5 — 15 mW on 



MARCH 1972 



115 



14 MHz and 15-30 mW on 28 MHz. This 
would be 35—45 dB down compared to my 
transmitter output, which is 1G0W. I 
looked through the specs of a few trans- 
mitters in this price and power bracket and 
found specs to read around —40 to -45 dB 
for harmonic suppression. So I was in the 
ballpark with my measurements. 

The Filter 

Surprisingly, none of the handbooks 
emphasized the urgent need for a low-pass 
filter to eliminate harmonics that go to the 
antenna. One would expect this to be just 
as standard as the transmitter itself. After I 
obtained my results on the cause of my 
TVI, I purchased a good quality low-pass 
filter. Good design, 1 should really say, 
because it has a few features that are 
essential if you want the filter to work 
efficiently - and which not all available 
low-pass filters have. 

Two most essential tuning adjustments 
are the input- and output-impedance ad- 
justments which are an asset if you want to 
avoid excessive power loss on transmitting 
and receiving. (See Fig, 1 for schematic.) 
Another important feature is the three 
tuning adjustments for channels 2-3^, 
4-5-6, and 7 & up. The filter manufacturer 
claims a suppression of 70 dB minimum for 
frequencies of 45 MHz and higher. This put 
my harmonics from 40 dB down to 110 
dB, which is about 1 nW in my antenna. It 
eliminated all my TVI problems except for 
channel 2 on my own set, but then — my 
TV antenna is right below my groundplane. 

This filter is a Radio Society of Ontario 
design and is manufactured by Taylor 
Communications, Uxbridge, Ontario. The 
price is $24,95 Canadian. It is not cheap, 
but it is effective. 



line, you have to use this type of coax for 
the interconnections. If you want to use a 
450£2 open feeder you have to install 
everything between transmitter and tuner. 
Now, before you start tuning you also need 
a dummy load. With all the equipment 
hooked up as in Fig. 1, first adjust the 
input and output impedance of the filter. 
Tune CI for a maximum forward reading 
on your reflecto meter, tune C4 for min- 
imum reflected on reflectometer. Repeat 
the adjustments several times. Your re- 
flected power should be less than 1%, or 
below 1.2:1 . 

The next adjustments are to get max- 
imum rejection of the interference fre- 
quency. To do this I turned on my TV set 
and switched it to the channel that I 
wanted to clear up, I increased the signal of 
the transmitter until the picture would get 
crossbars. Then I started to tune the 
related C on the filter in small increments. 
After each incremental adjustment I re- 
peated the tuning procedure for CI and C4 
to maintain the low swn Since I did not 
have any TVI at TV channels 7 & up I 
simply adjusted this C5 for maximum 
forward deflection. 

After tuning the filter according to this 
procedure, I eliminated TVI on channels 3, 
4, 5, 6; only 2 remains somewhat a 
problem in my own house. Neighbors of 
4nine who had TVI before do not have any 
at all. One chap with a color TV can 
merely see a faint change in color on 
channel 2, 

You will find that you might not have 
the optimum filter setting when optimizing 
for one particular frequency. In my case, 
when tuned for 20m 1 found swr tuning 
was not quite maximized on 15m and 
somewhat more off on 10m, I set my filter 



How to Tune the Filter 

The success of the filter depends on 
how well you tune it, and to do this you 
must have an swr bridge or some kind of 
reflectometer. The best way to set it up is 
as Fig, 2 shows. From your transmitter you 
should go through your refleetometer to 
the filter, from there to the antenna, Since 
the filter is designed to work in a 5 0-75 Q> 




OUT 



Fig, 2. Schematic of filter. 



116 



73 MAGAZINE 



^*- 




6" coax 



cnz 



$ 




\ 



Cftf 



\ 



o ;out 



wv 



LOK 




IOOjv 



I 

1 



,01 f^A J 0-100 



x — 

Fig. 3. Schematic of re flee tome ter. CR1 and CR2 
are any matched pair of silicon or germanium 
diodes. 

to compromise between the 3 bands. With 
a dummy load, reflected power on a 
compromise setting reads between 1 and 
2% depending what part of the bands I use- 
Switching to my groundplane antenna, I 
am getting between 2 and 6% power 
reflected. 

The Reflectometer 

The reflectometer I used (Fig. 3) is a 
modified version , as the one listed above. 
As a conductor and pickup I used 6 in. of 
RG-8/U coax with two insulated wires 
pulled into the braid. This is less of a 
mechanical job than the original of W4BRS 
(73, Sept. 1967). As for the meter scale, I 
also calibrated it in "% reflected." This is 
more meaningful to me than swr. 
Dial calibration based on a 100% meter 
scale: 



Scale % 


= SWR 


= % reflected power 
(coax losses disregarded) 


9 


1:1.2 


.8 


20 


1:1.5 


4.0 


33 


1:2.0 


10.5 


43 


1:2.5 


185 


50 


1:3.0 


25.0 


60 


1:4 


36.0 



The Dummy Load 

This dummy load (See 73, Feb. 1968, 
WA60BH) was built and I found it can 
take 80W rf for quite some time. However, 
I do not advise you to use motor oil for 
coolant, since its dielectric constant is 
much to low because of inorganic addi- 
tives. ...VE3GSP" 



T 2 L IC'S 



7400, 7402, 7404, 7405, 7410, 7420, 7430, 

7440, 7450 . . $ .3^ 

747T 7474 fi^ 

7476 75 

7441 , 7481* 7492", 7493, 7495", 7496. 

8281 1.50 

7490 1 40 

7475 t9 . mm 1.25 

74192, 74193, 8280, 8270, 8277 2.00 

8251 1 90 

LIGHT EMITTING DEVICE 

MAN-T equiv. 7 segment display 14 DIP 
package „...'.*„• 3.50 

RELIABILITY SUPPLY 

P.O. Box 805, San Carlos, California 94070 

TERMS: Orders over $10.00 will be post- 
paid—add $ .35 handling and postage for 
smaller orders. C.O.D. — add 25%. California 
residents add 5% sales tax. 



WE PAY HIGHEST CASH PRICE 

for Electron Tubes & Semiconductors 

Immediate Payment on Unused Tubes 

H & L ASSOCIATES 

Elizabethport Industrial Park 

Elizabeth, New Jersey 07206 

(201) 351-4200 



WORLD QSL BUREAU 

5200 Panama Ave., Richmond CA USA 94804 

THE ONLY QSL BUREAU to handle all of 
your QSLs to anywhere; next door, the next 
state, the next county, the whole world. Just 
bundle them up (please arrange alphabetically) 
and send them to us with payment of 54 each. 



ONE COMPLETE SOURCE 

SPECIALIZING 



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We stock crystals 
and parts for all sets we sell 



— Write for free literature — 

DALE ELECTRONICS CORP. 

244 West 14lh St.. New York, N.Y. 10011 
Free Parking 212-255-3660 



MARCH 1972 



117 






INTEGRATED CIRCUITS 

FACTORY FRESH — NO REJECTS 
W/SPEC, SHEETS 

FAIRCHILD — RHILCO — RCA 

MOTOROLA — NATIONAL 



NEW LOW PRICES 
RTL or TTL LOGIC 



nirr inn ■ >-* ■■ ■■ ■ ■■-!- ■■■*■.»■ 



I lill l lTTlT I I ■ ■ ■ ■ ■ ■ li »fc*l ■ ■"■ ■ 



SO* 10/5.50 
80c 10/5.50 



UL 900 Buffer 

UL 914 Gate . 

UL 923 JK Flip-flop $1.50 10/8.50 

IIC 790P Dual JK Flip-Hop $2.00 10/18.95 

iiC 890P Dual JK Flip-flop $2.00 10/18.95 



MC 780P Decade 
MC 767P Quad Latch 
MC 9760P Decade .... 



!■■■«■,.», i i i u j«i i| | ■ || HiiJ ^i m ■ 



■ ■ ' ' *m 



$3.00 
.. 3.00 
.. 5.00 



ONE EACH OF 3 ABOVE $10.50 



7400 Quad 2 Input NAND Gate 65<* 10/5.95 
7404 Hex Inverter ™ 65* 10/5.95 



7441A Decimal Decoder/Driver 

$3.50 10/29.95 
NEW!! 7447 7 Segment Decoder/Driver 

$3.10 each 10/$27.95 

7473 Dual JK Flip-flop $1.30 10/10.95 

7475 Quad Latch „,.. $2.10 10/19.95 

7490 Decade Counter $2.40 10/19.95 

741 Op Amp _$2.70 10/25.00 

CA 3035 Linear Amplifier $2.25 10/21.95 

LM 309K 5V Regulator $3.75 10/$34.95 

14 Pin Dual Inline socket terminals 

25 $ 10/2.25 

16 Pin Dual Inline socket terminals 

30tf 10/2.75 



NEW NATIONAL Long Life Nixie tubes NL 
940S 0-9 with two decimal points 

$4.50 ea. 10/42.95 

SOCKET for NL 940S .-• 50^ each 

100 KC CRYSTAL NEW . $3.95 



88 MH TOROIDS 



10/3.00 



Miniature read switch glass enclosure %" 

long. ^^ «— — — — *~~~^_ 35 ea. 10/$3.00 




R & R ELECTRONICS 

311 EAST SOUTH ST. 

INDIANAPOLIS, IND. 
46225 

$5.00 minimum order. 
Please add sufficient postage. 



COOLING FAN BLOWER 4 pole 110V 60 eye 
motor with 4 bladed nylon fen. Very quiet, 
about 50 CFM 2V 4 "W x 3"H x 2V4"D. Sh. 

wt- 3 lbs „ „ , .. ^ m $2.25 each 



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ARN-30 108*135 mc tunable receivers. High 
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RADIO RECEIVERS R-257/U 

BACK WITH AN EVEN BETTER SUPPLY 

R & R has the Motorola Plug In's we sold 
out of last year and more. 

We now have the popular LOW BAND 25-50 
MC equipment. Unit comes with these 
plug-ins: 

. 1st IF & 2nd Mixer 

• RF & 1st Mixer 

• Oscillator Doubler unit-Amplifier 
■ 2nd IF & Discriminator 

• Audio Squelch 
. Filter Unit 

SCHEMATIC Diagrams for all units supplied 



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Robert L. Morgenstern WA2EAW 
141-60 73rd Ave. 
Key Gardens Hills NY 




100. . . 

Addingthe400 Hertz CW Filter 



— any operators like to work both CW 

and phone. The HW-100 is supplied 

with the SSB filter only. Heath states in 
the HW-100 manual that the CW filter can 
be placed in the rig, but at the cost of 
leaving out the SSB filter. This of course 
leaves the transceiver good for CW only. 
Many operators, like myself, operate both 
CW and phone, so of course I put in just 
the SSB filter. Being very human, I later 
decided it would be nice to have a narrow, 
400 Hz slot for CW. This, of course, was 
realized after the rig was completed. I 
spoke with some boys who placed the CW 
filter into the completed HW-100, doing it 
as it is done in the SB-101, This is a 
herculean task in the completed rig, but it 
can be done. 

After reviewing the circuitry, Fig. 1, and 
the method of mechanically performing 
the switching of either filter in or out of 
the circuit in the SB-I01, 1 felt there must 
be an easier way to do it. The following 
modification is easier, faster to install, and 
cheaper. I spent 494 over t^ e cos * of the 
filter and a new matching panel knob. 

Modification Procedure 

Additional parts needed: 

1 . CW filter with mounting nuts, 

2. Matching panel knob for HW-100. 

3, Rotary wafer switch containing the 
equivalent of 3 SPDT contacts (Fig. 2). 

4, New mounting bracket for filter. The 
old one can be redrilled, as I did, to 
accommodate the two filters as both filters 
are physically identical and the bracket for 
both filters is the same as the CW bracket 
alone, except for the holes being in differ- 
ent places. 



Considering the frequent use of both 
filters at my QTH, front panel installation 
for the switching of the filters was needed. 
Since the mike will usually remain connect- 
ed, access to the mike connector was of 
secondary importance. 

The PTT mike connector, at hole M on 
the front panel, was moved to the left rear 
apron where the unused hole was enlarged 
to receive it. Additional hookup wire was 
used to lengthen the circuitry resulting 
from the move. The wafer switch was 
placed in the hole M. The CW filter was 
mounted on the filter bracket with t lie SSB 
filter. The two capacitors, C506 and CI 01 
and the resistor R929 are not connected to 
the fJter, only to the circuit board points 
as instructed in the HW-100 manual. The 
remaining connections of the capacitors 
and the resistor will be done on the wafer 
switch as in Fig. 2. Make sure the lugs of 
the phone jack at hole L does not contact 
the lugs on the wafer switch. Bend the lugs 
away as needed on the phone jack. All 
leads from the wafer switch to the filters 
will pass through grommet CA for neatness 
and ease of installation. 

Ground connections can be made at any 
convenient point. R929 went to the 
ground foil of the modulator board. The 




OUTPUT 



INPUT 



Fig. I. Schematic for CW and SSB filters in 
SB-1Q1* 



MARCH 1972 



119 



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NO 14 

Fig. 2. Schematic/pictorial forCWand SSB filters 
mHW-100. 

Ci A" ground (Fig. 2) I put to a bolt holding 
the modulator board to the chassis, insula- 
ted wire was used and sleeving as needed to 
prevent unnecessary bare wire exposure, 

I strongly suggest that if the original 
filter bracket is going to be redrilled as I 
did, that you remove the bracket from the 
rig, even though it means removing the 
VFO also, This little extra work will save a 
load of time, effort and possible expense in 
trying to find short circuits and /or result- 
ant damaged components caused by those 
small bits of metal dropping into the works 



of the rig. Also do not try to get away with 
the grounding on the input side of the 
filter when not in the circuit. These filters 
have, I am told, bifilar windings. Because 
of the close coupling of these two filters, 
induced emf can be generated in the filter 
while not in use. This in turn will create its 
own field which will affect the filter in the 
circuit- This induced emf in the unused 
filter must be removed and is done so by 
grounding. You can count on this to 
hamper the filter qualities and to interfere 
with good receiver operation. 

The advantage of this method of instal- 
lation is that the front panel does not have 
to be pulled away from the chassis. This 
can be a big undertaking for the type of 
switching used in the SB-101 because the 
wires are short on the band and mode 
switches on the front panel of the com- 
pleted rig. Besides, the purchase of the 2 
slide switches and the mechanical linkages 
for the switching of filters as in the SB-101 
will cost far more than the 494 I spent for 
my wafer switch, 

. . ,WA2EAW 



V ibrople X 




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120 



73 MAGAZINE 



CQ U.S. with 

PHONE PATCH TRAFFIC 



Ralph Steinberg K6GKX 

Dial one one zero on your telephone and 
a pleasant voice answers, "Operator." This is 
nothing unusual except when a phone patch 
is being arranged by a long distance operator 
for some serviceman to talk to his family 
from Vietnam, 

Thousands of phone patches are beamed 
daily to the United States by MARS stations 
in Vietnam. Handling thousands of phone 
patches takes team work; the long distance 
operator, the overseas radio operator, and 
the station in the United States receiving the 
overseas calls make up the team. 

It is fascinating to see at first hand how 
these operators work the long distance switch- 
boards The girls have boards with switches, 
jacks, and plugs. Each position has nine 
incoming and nine outgoing circuits and 
each operator is responsible for these cir- 



cuits. If phone patching is in operation, each 
operator can handle nine calls at one time, 
To keep the calls moving smoothly, the 
operator always has another ready to talk 
when the proceeding call is finished. Usually, 
on phone patch operations, one operator 
will stay on the circuit until all phone patch 
operations are completed. 

All phone patch calls are not just routine 
and many times the operator has difficulty 
in locating the person to receive the call. 
Frequently calls are for families living in 
small villages in mountain areas far from a 
long distance phone line. The operator will 
try to locate the nearest long distance phone 
so that the phone patch can be completed. 
Often company officials have assisted in 
locating hard-to-find parties, sometimes at 
all hours of the night. 




Fig. I, View of long distance telephone switchboard operations. Pacific Telephone 
Co, photo. 



MARCH 1972 



121 




Fig, 2. Phone patching at MARS station K6WAH/AA6WAH, U.S. Army photo. 



A serviceman in Vietnam was calling his 
family, and the long distance operator 
advised the father that she had a collect call 
from his son and would he accept the call* 
The father refused the caU thinking someone 
was joking until the operator explained it 
really was his son on the line and the father 
then accepted the call. It was a happy and 
exciting event as this was the first call the 
family had received since the son left home 
to go overseas. They were unaccustomed to 
receiving phone patch calls, especially col- 
lect. On other calls proposals of marriage are 
heard several times a day. As one serviceman 
proposed, the sound of guns could be heard 
in the background. 

Drama has an equal share in the phone 
patching. One call from a serviceman to his 
wife was never completed as she was among 
the missing in a plane crash. There are also 
calls to the families by the servicemen, 
explaining that they have been injured, but 
not to worry, One serviceman was talking to 
his wife and asked if the new baby had been 
born. When he learned that triplets were 
born, the telephone line went dead on his 
end. He had fainted. 

The long distance operators are exceed* 
ingly interested in the phone patch work 
they are doing. They, too, have sweethearts. 



husbands, brothers or sons in the military 
service, and frequently receive phone patch 
calls from them. These girls take their work 
very seriously , and even with all the thou- 
sands of phone patch calls they handle, each 
call has some feeling of excitement attached' 
tb it. 

Most phone patch traffic from Vietnam is 
received on the west coast at MARS stations 
from San Diego, California, to Ft. Lewis, 
Washington. In southern California, there are 
more than twelve MARS stations located on 
Army, Air Force, and Navy installations. 
Many thousands of phone patches are com- 
pleted each month through these stations, 
with additional calls being handled through 
radio amateurs, members of the Military 
Affiliate Radio System. One of the busy 
MARS stations in the Long Beach, Los 
Angeles area is K6WAH/AA6WAH at Fort 
Mc Arthur, with radio operators on duty 
twenty-four hours a day. This station com- 
pletes an average of 4000 phone patches a 
month. 

It was not my purpose to glamorize the 
long distance operators, but to commend 
them for the fine work they are doing to 
keep up the morale of our servicemen. 

. K6GKX ■ 



- - 



122 



73 MAGAZINE 



QUI 

Try Any of These Modern, Comprehensive License Books on 10-Day FREE Trial! 



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I Teaches, in simple 
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SOLID STATE PROJECTS 
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■■■i^lHi * 3 projects are of interest 

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7-Segment digital Readout $3.70 

SN7400 Quad 2 input NAND gat© .35 

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SN7410 Triple 3-input NAND gate 35 

SN7420 Dual 4-input NAND gate # # 35 

SN7430 8 input NAND gate 35 

SN7441N NIXIE decoder/driver . 1.50 

SN7447 7 segment decoder/driver 2,25 

SN7473 Dual J-K FHp-Flop SB 

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MC724P RTL Quad gate 1 .00 

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MPS6512, MPS6516, Solid state RTTY terminal unit 
FSTU-1A $34.95, Solid state power supply for above 
PS-1A $12.95. ARC R19 rcvr 118-148 MHz complete 
w/schematic $14.95. Pottor & Brum fie Id industrial control 
relay KU -4129-2. 115VAC 60 CPS coll, new 75* ea. 
Projection lamp 750 W, 115VAC T12-C130 base up. DC 
med. ring: New $1.75* Hand telephone and mounting 
assembly 600 ohm $4.95. 

CATALOGUE 10* 

FRANK ELECTRONICS 
407 Rlttar Road, Harrlsburg, Pa. 



^m 



ALL BAND TRAP ANTENNA ! 



■ " m m <* 

akea v W 

akes W For fi 





Reduces Koise on All 
Short Wave Eece Ivors. 
World-Wide Reception 



Make 
Makes 



For ALL Amateur Transceivers* 



Better, Guaranteed for 100O Watta 

Complete with 96 ft. 72 ohm I Power. Inconspicuous-Efficient! 
feedltne. Sealed resonant traps. For novice and ait class radio ama- 
teurs! Eliminates 5 separate antennas with excellent performance on 
all ©0-40-20-15-10 meter bands. Complete 102 ft, 519.95. 40*20- 1 P- 
10 meter bands,. 54 ft, (beat for world-wide abort wave reception) 
Si 8. 95, Send only $3>oo (cash, ck, mo) and pay postman, balance 
COD plus postage on arrival or send full price for post-paid delivery. 
Complete Instructions included. 
WESTERN ELECTRONICS "Dept. A, Kearney, Nebraska 98847 



124 



73 MAGAZINE 



Neil Johnson W20LU 
74 Pine Tree Lane 

Tappan NY 10983 



Confessions of a Surplus Hound 



Some hams are builders and prefer to 
experiment, some do otherwise. This 
article is dedicated to the first group. Before 
the war, ] got started in the ham game • . ( 
scrounged and swapped for parts and made 
do with whatever was available. Slightly used 
Weston meters at $3 each, secondhand mid- 
get tuning condensers at 50^ . . . that sort of 
stuff. 

Came the war and the subsequent flood 
of surplus equipment , some good and some 
not so good, but all of it very cheap. 
Incredible bargains! An awful lot of that 
stuff found its way into my basement, I had 
accumulated so much junk that prior to 
moving to the new location several years 
ago, 1 started six months early to swap, sell 
and give away all the gear that couldn't be 
carted to the new QTH, Resolved never to 
let it happen again! But it did. Maybe that's 
because I'm hooked on surplus ... at any 
rate, here are a few useful tips. 

As I said, there is some very good stuff on 
the surplus market and some not so good. If 
you should buy a damaged night-light con- 
trol and fool around and fix the thing, that's 



all right. Even though you may never use it, 
you've learned something. But never buy a 
piece of gear just because it looks nice. 
Otherwise you will end up with a shack full 
of surplus and no room in which to put your 
operating equipment. Don't laugh, please. 
This has happened to stronger men than 
you! 

Where to purchase the surplus? When 
Cortlandt Street - New York's oldtime 
"Radio Row" — was in existence, it was 
quite simple for thousands of bargain- 
minded hams to snoop and shop, to visually 
inspect the gear that was for sale. Today 
Radio Row is but a fond memory but this 
illustration points up rule number one: See 
before you by. This might be impossible in 
certain cases, so we go on to rule number 
two: If your buddy bought an item from a 
particular surplus merchant and was happy 
with the deal, the chances are good that you 
can buy the same or similar gear from the 
same outlet with satisfaction, I can now hear 
you asking "What happens if I can't apply 
rule number one or rule number two?" 



MARCH 1972 



125 



MORE RANGE . . . 



NOISE 



WO*^ 



\)Ntf S 



S*«E 



;-v i*; 



,WI 



■I* I ■ * 



Mph' 



ELECTRO 
SHIELD 



CUSTOM SYSTEMS 
KITS •ACCESSORIES 



ELIMINATE IGNITION NOISE 

ELECTRO -SHIELD* 

YOUR ENGINE 



FROMS44.95 



ESTES ENGINEERING CO. 

543 W. 184th St., Gardens, Calif. 90241 



DOUBLE YOUR 
RANGE! 

Four times the POWER equals 
twice the range — 

2m FM Amplifier 

4/12 W IN - 20/50 W OUT 

Matches DRAKE ML, SWAN 

1210, Tempo FMV, IC2F, SCR 

826M, Regency HR2, Sonar 

3601, SB-144, Simpson A, Ross 

& White, etc. All automatic TR 

switching. 

7x5x3. Order direct . $119.95 

VHF Specialists Box 197 
VIENNA, VIRGINIA22180 



*■ 



Tell Our Advertisers 
You Saw It In 73 
(Even if you didn't) 



You could take pot luck and perhaps end 
up unhappy. But there are a few angles 
whereby you can tip the odds in your favor, 
No guarantee of success, mind you, but a big 
improvement in your chances. Take a close 
look at any surplus hound's catalog file. 
Along with all the popular mail order cata- 
logs you will find catalogs from some of the 
larger surplus houses. This is usually a good 
sign, for it shows that this particular firm 
thinks enough of its customers to go to the 
time and trouble to assemble, print and 
distribute a catalog. What with annual or 
more frequent updating, this all takes time, 
money and effort. These firms put out these 
catalogs because they want you to be a 
satisfied customer. Also, when you receive a 
catalog, many of the items are illustrated. 
This works in your favor, since you will have 
a fairly good idea of what the gear looks like 
before you buy it. In a catalog there is room 
for a description, plus specs such as size, 
weight, color and so on. Less chance for 
misunderstanding. 

Other merchants operate along slightly 
different lines. That is, they do not feel 
justified in making up and issuing a catalog 
at regular intervals. This is particularly true 
in some cases where the firm specializes in 
big-ticket items, fewer in number, such as 
HF receivers, used oscilloscopes and rela- 
tively expensive test equipment. The major- 
ity of firms that advertise are ethical, and in 
case you are disappointed, a letter to the 
firm in question will usually rectify the 
situation. The chances of your getting 
burned are greatly reduced if you will follow 
these simple rules. Why shouldn't you profit 
from someone else's mistakes? 

I have been well served by many of 73's 
advertisers, among them Meshna, Fair Radio, 
Jefftronics and Columbia to mention just a 
few. In the old days I was forced to buy 
surplus in order to save money. Now I find 
that I buy the stuff to save time and trouble, 
not to mention exasperation, since the near- 
by radio stores don't always carry the 
particular parts needed. What's that saying 
by the French to the effect that 4 The more 
things change, the more they become the 
same?" 

W20LU 



126 



73 MAGAZINE 



Buy Anv 3 

Take 10% 
Discount! 



GIANT SALE ON NEW TTL 
TEXAS A NATIONAL ICs 



O >* 



S 



Type 

□ SN7400N 
D SN7401N 
D SN7402M 
Q 5N7404N 
Q SN7405N 

D SN7410M 

SN7420N 

Q SN7430N 

□ SN7440N 
Q SN7441N 

□ SN7446N 
C SN7447N 
D SN7473N 
D SN7474N 
P SN747SN 
D SN7476N 
G SN7461N 
Q SN74S3M 
D SN74SON 
G SN7401N 
D SN7492N 
D SN74MN 
f SN7494N 
fl 5N749SN 
(1 SN74154N 
a SN74181N 
LJ SN74192N 
G SN74193N 



Function Sale 

Quad 2 input NAND gate . , 
SN74O0 with open collect . . .39 
Quad 2 input NOR gat* .... 

Hex Inverter , * , . , „ , 

Hex Inverter, open collect . . 
Triple 3 input NAND gate . . 
Dual 4 input NAND gate . , 
9 Input NAND gate ...... 

Dual 4 input NAND buffer . . 
BCD -to- Decimal driver . . . . 

BCD-to-7 seg, dee, /driver 
BCD-to-7 *eg. dec. /driver 
Dual J*K Matter slave flip-flop .69 
Dual D triggered flip flop ♦ , .69 

Quad bistable latch . . . 1.50 

SN7473, with preset-a-clear .69 
16-bit memory {scratch pad) 1.50 

4-bit binary full adder 1.96 

Decade counter 1.40 

8- bit shift register . 1.25 

Divide by 12 counter ...... 1.25 

4-bit binary counter ,,..,., 1.25 

4- bit shift register 1.25 

4-bit register right- N- left , . ISO 

Divide by 16 3.45 

Arithmetic Logic Unit ..... S*S0 
Bi -directional counter . . . . 3,45 
Binary up down counter . . . 3.49 



BRAND NEW! LINEAR IC AMPS 

factory Guaranteed! Factory Marked! Factory Tested 

T*vne ne.scripLJnn Sale Suit* 





SN5510L 4DMZ, Video Amp . 

702 Hi Gain, DC amp TO-5 

703 RF-IF, 14 hookups, TO-5 . 
709C Operational Amp*** . . . 
710C Differential Amp*** . 4 , 
7 11C Memory. Sense, Amp*** 
723A Voltage Regulator *** 
TVR-2000 Hi-power 723 *•* 
741C Freq. Cornp. 70S*** , . . 
74BC Freq. Adjustable 741*** 




709-709 
741-741 
749-749 
741-741 



Dual 709's (DIP) 



Dual 74l*s (DIP) . . 
Stereo Preamp (DIP) 
Dual 741's (DIP) . . 
16 Transistor stereo 
PREAMP (DIP) 
Dual channel audio 
amp (DIP) 

#** State 1st, 2rid choice, Dua 



□ 739-739 
D 749-749 



for 0.OO 
for 2.00 
for 3.00 
for l.OO 
for 1.00 
for l.OO 
for 3.7 5 
for 3.9S 
lor 2.50 
for 2.50 
for 4.00 
for 5-50 
for 5. SO 
for 6,00 



. . 2.49 3 for 6.0O 



49 3 

Line, 



for 6.00 

TO-5. 



INTEGRATED CIRCUIT SOCKETS 



Buy Any 3 



Take 10% Discount! 

line 



D 14-Pin, dual in line . .$.45 
D 19-Pin v dual in line - - -SO 
□ TO-5, 8 or 10 pins . - . .29 




6-AMP FULL WAVE BRIDGES 



TRY 
SO 
100 

200 



400 

D 600 
D 800 
□ 10OO 




^ 




"AMATEUR" 400 MC NPN 
HI-POWER TRANSISTOR 

□ Only $2,95 Buy 3 T * k » *0 * 

TO-60 case. Simitar to 2N3S32 . 400 mc, 
3 amps, 60 bvcho, IDO hfe 2 3 watts, 



NATIONAL LM-565 
PHASE LOCK LOOP ICs 



Only 54.95 D ° u *' ln Lin * □ TO-5 Case 






m/M 



SILICON" TUBES 



SU4 $1.49 

866 7.95 



Q15$ CATALOG on Fiber Optics, 'ICs', Semi's, Parts 




ALPHA-NUMERIC 

7-SEGMENT 

READOUTS 



3.95 



-*_J 



Buy any 



Take 10% Discount 




A Poly Pak exclusive! Two different types. Both 
compatible with SN7446, SN7447, SN7448, 
SN747 5, SN7490 and SN74192 ICs. Both with 
decimals, O to 9 numerals and 10 letters. With 
specs & hookups- 

G 16-PIN MICRO MINIATURE 

Fits Into 16 pin dual in line socket. Life: 250,000 
hours. Delivers 700-ft. Lamberts brlteness with 
5 volts 8 mils per segment. Characters .362" H. x 
.197" W 

□ 9-PIN TUBE TYPE 

For printed circuit board or socket. Life: 100,000 
hours. Delivers 6,000-ft* Lamberts with 5 volts 
23 mils per segment. Characters .47" H. x .26" W. 



7-SEGMENT □ 

ALPHA-NUMERIC $6.50 

LED READOUT 3 for«is L . . . 

1 r 

0-9numoer5 and 9 letters, Compatible withSN7446 
and SN7447 7 -segment BCD IC drivers. Snaps into 
dualin line sockets. Only V 4 x */ 4 x V*"- Specs: 5V 
20-mils. 





FAIRCHILD "VISIBLE" LED r s 
Buy 3 Take 10% Discount! 

■*, Color: Red. For readouts, panel 
*"* lights, etc. TO- IS case. 



o.oo 




n SOLID STATE 
AM-FM TUNER 



WESTING HOUSC 

3 for $10 



FM 88-l08mhz & AM 550- 
16 00kcs. Sensitive 2 a / 4 x 2 V4 
x IV2" module. Can be used 
with 10,7mc & 4 5 5kcs IF 
strips & any hi-fi amp. F*C*, 
wired, 4 -gang variable sup- 
pry voltage 9V 6 mils. Yarac- 
tor diode for AFC, Schematics. 



ALLEN BRADLEY'S 
'TRANSISTOR' POTS 

Type F, Screwdriver adjust. 
Ohms 

□ 100 □ BOO D2.5K O 20K □ IOOK Q 500K 
D200 □ 1.OKQ5.OK D 25K D200K Q 1 Meg 

D250 n 2-OK QlOK Q 50K Q250K D 2 Meg 




'MICRO-POTS' 

2 for $1 

Ohms 

D 100 D i-0K 

□ 250 D25K 
D 500 □ 5.0K 



Type C, 1/2" diu. x 
1/2" high. Mounts 1/4" 
hole, with shaft, linear, 
imirfeTsion-proof high 
fre<|. 

D 10K □ 100K □ 1 Meg. 

D25K D 250K □ 2 Meg. 

□ SOK □ 500 K □ 5 Meg. 




EPOXY SILICON 

RECTIFIERS *rtilcramini 

p| V 2Amp * 

50 $.05 

100 .06 

200 .07 

400 .09 

600 .12 

800 .15 

IOOO .16 



2Amp 


3 Amp 


S-05 


S-08 


.06 


.12 


,07 


.15 


.09 


.22 


.12 


.28 


.15 


.39 


.10 


.45 



HIGH VOLF 

Ptv i AMP SALE 
2000* 1.00 

3000 135 

H 4000 1.65 

5000 2.25 

J 6000 2,96 

□ 8000 3.50 

10000 3.95 



COUNTING 
SYSTEM 



rncLudes SN7 4 0O dec- 
ade counter, SN747 6 
latch, SN7441 BCD de- 
coder-driver, and a 
Nixie* tube that indi- 
cates to 3, 1 its true - 
t inns. 



4-Pc. Kit 

6.66 





Terms? add post age , Rated: net HO, rod's 25 r i k 
Phone Orders: Wakefield, Mass. (617) 245-3K29 
Retail.* 211 Albion St, f Wakefield, Mass. 

P.O. BOX 942 A LYNNFfELD, MASS 01940 



READER SERVICE 

Please either tear out this list of advertisers and send 
it in to 73 with as many boxes checked off as you 
would Like to see brochures, data sheets or catalogs . . . 
or else make a copy and send that in. Do NOT fail to 
send for data on those products and services that 
interest you. Your magazine will be as large as the 
number of ads allow it to be • , . so the more you 
encourage the advertisers the bigger magazine you will 
have. When you send for information, the advertisers get 
encouraged* Send, 

ADVERTISER INDEX March, 1972 



□ Adirondack 68 
D Allied 26 

n Amat. Elec, Supp. 59 

a Amat. Wholesale Elec. 124 

□ Amer. Xtal 105 
D Antek 120 

□ Arnold's 78 

□ ATV* 120 

□ Avcom 44 
a Babylon 97 
a B & F 80 

□ Bomar 68 

□ Brigar 96 
c B & W 74 

□ Call book 67 

□ C & H 99 

□ Circuit Specialists 91,124 
n Columbia 85 

□ Corncraft 51 

D Commun. Spec. 78 

□ Cornell 74 

D CushCraft 24 

□ Dale 117 

□ Data 74 

D Dayton 120 

p Denson 94, 95 

□ Derrick 74 

□ Environment. Prod. 82, 83 
a Epsilon 78 

a E.S. Enterprises 17 

a Estes 126 

D Frank Elec. 124 

□ G &G 81 

a J J. Glass 79 

□ Goodheart 124 

□ Gray 100 

□ Gregory 84 

□ Hal 72, 106 

□ Hatry 24 
D H&L 117 

□ Heath 45 

□ Henry Cover IV 

□ Jan 102 



□ Janel 120 

□ Jefftronics 102 
a Jensen 124 

□ Juge 61 

O K-Enterprises 106 

□ Landry 74 

□ Mann 88 

n Meshna 90 

□ Mini-Products 28 

a Mtn. West Alarm 124 
D Nu Sigma Alpha 44 
c Palomar 60 

□ Payne 78, 106 

D Pearce Simpson 71 

□ Poly Paks 127 

□ Projects Unlimited 105 
n Propagation Prod, 98 

□ Quaker Elec. 124 

□ Reliability 117 
D RP* 60 

a Savoy Cover II I 

D Sentry 52 

D Slep 92, 93 

Q Sonar 35 

n Standard Cover II 

D Standard Elec. 89 

a Tab 123 

n TaNen 86, 87 

n Tefrex 22 

D Vanguard 17, 38 

n VHF 126 

D Vibroplex 120 

□ Wentworth Press 18 

□ Western Elec. 124 

□ Wolf 105 

□ World QSL 117 
73 Stuff 

Subscriptions 46, 47 
Radio Bookshop 62, 63, 
TV I 66 

Rptr, Circ, Man. 70 
Rptr. Bulletin 112 



64 



* Reader Service inquiries not solicited. Correspond di- 
rectly to company. 



Mail to: 73 INC, PETERBOROUGH NH 03458 

PLEASE PRINT OR TYPE 



Name 



Call 



Address 



Zip 



PROPAGATION CHART 

J. H. Nelson 

Good (Open), Fail- (O), Poor I I 

March 1972 



SUN MON TUES WED THUR 



FRI 



1 2 



5 



6 © 8 



9 




SAT 



4 





15 16 17 18 



19 20 

26 21 




24 25 



30 31 



EASTERN UNITED STATES TO: 



GMT: oo oa 04 oe 03 io 12 14 te ia 20 ai 



ALASKA 



ARGENTINA 



AUSTRALIA 



CANAL ZONE 



ENGLAND 



HAWAH 



INDIA 



JAPAN 



MEXJCO 



PHILIPPINES 



PUERTO RICO 



SOUTH AFRICA 



U. S £ R. 



WEST COAST 



14 



14 



21 



14 



21 



H 



t4 



14 



14 



14 



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14A 



14 



14 



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14 



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14 



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76 



7B 



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7B 



7B 



76 



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76 



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76 



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14 



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14 



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14 



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21 



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[CENTRAL UNITED STATES TO: 


ALASKA 


14 


14 


?A 


7 


7 


7 


7 


7 


7A 


14 


14 


14 


ARGENTINA 


14A 


14 


14 


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7 


7 


14 


21 


21 


21 


21 


21 


AUSTRALIA 


21 


21 


14 


7B 


76 


7 


7 


7 


14 


14 


21 


21 


CANAL ZONE 


2T 


14 


7 


7 


7 


7 


14 


21 


21 


21 


21A 


21 


ENGLAND 


7 


7 


7 


7 


7 


7 


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14 


14 


14A 


14 


14 


HAWAII 


21 


21 


14 


7 


7 


7 


7 


7 


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71 


21 


INDIA 


7 


14 


7B 


78 


7B 


7B 


76 


7B 


14 


7 


7 


7 


JAPAN 


14 


14 


70 


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7B 


7 


7 


7 


7 


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14 


MEXICO 


14 


14 


7 


7 


7 


7 


7 


14 


14 


14 


21 


21 


PHILIPPINES 


14 


14 


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7B 


7B 


?U 


7S 


7 


14 


14 


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14 


PUERTO RICO 


14A 


14 


7 


7 


7 


7 


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21 


21 


21 


21 


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SOUTH AFRICA 


14 


7A 


7 


7 


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7B 


M 


21 


21 


21 


21 


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U.S. Si R. 


7 


7 


7 


7 


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7B 


14 


1,5 


14 


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WESTERN UNI1 


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STATES TO: 








ALASKA 


14 


14 


7A 


7 


7 


7 


7 


7 


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14 


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ARGENTINA 


21 


21 


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7 


7 


7B 


14 


21 


21 


21 


21 


AUSTRALIA 


21 


21 


21 


14 


7A 


7B 


7 


7 


M 


14 


21 


21 






14 


7A 


7 


7 


7 


7 


14 


21 


21 


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21A 


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21 


ENGLAND 


7B 


? 


7 


7 


7 


7 


70 


7B 


14 


14 


14 


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HAWAII 


21A 


21A 


21 


14 


7A 


7 


7 


7 


14 


21 


21 


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INDIA 


7 


14 


14 


7B 


7B 


7B 


7B 


7B 


7 


7 


7 


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JAPAN 


21 


21 


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7B 


7 


7 


7 


7 


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21 


14 


7 


7 


7 


7 


7 


14 


21 


21 


21 


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21 


14A 


14 


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7B 


7B 


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7 


7 


14 


73 


14 


PUERTO RICO 


21 


14 


7 


7 


7 


7 


7 


14 


21 


21 


21 


21 


SOUTH AFRICA 


14 


7A 


7 


7 


7B 


76 








21 


21 


1 4A 


7B 


14 


21 


U. 5, S. R. 


7B 


7 


7 


7 


7 


76 


7B 


7B 


14 


14 


7B 


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14A 


14 


7 


1 


7 


7 7 


14 


21 


21 


' 21 


21 



m» 



A = Next higher frequency may be useful also. 
B = Difficult circuit this period. 



128 



73 MAGAZINE 



For incomparable 2 meter coverage 







■ ^ f 




MODEL DGM-2 

An extremely lightweight sparkling 
white fiberglass sealed phased mobile 
collinear antenna with a BIG punch 
on 2 meters. 

Threaded 3 / 8 ~24 to fit any standard 
bumper or body mount. Factory ad- 
justed and ready to go. 

MODEL DGM-2 $39.50 



MODEL DGF-2 

For repeater and fixed station use on 
2 meters. Same collinear system as 
the DGM-2 but complete with fiber- 
glass radials and pipe mount with 
PL-259 standard coax connector. 

installs on standard % pipe mast 
with provision for coax line inside the 
mast. Factory adjusted and ready to 
go. Mast not included. 

MODEL DGF-2 $79.50 



CONTACT YOUR DISTRIBUTOR OR WRITE FOR DATA 
ON QUARTZ CRYSTALS AND ANTENNAS 



v^*i' 



lecfcronics.lnc 



P.O. Box 71 57 - Fort Lauderdale, Florida - 33304 

Tel: 305-566-8416 or 305-947-1191 




THE MOST EXCITING RECEIVER AND TRANSMITTER TO ENTER THE AMATEUR SCENE IN RECENT YEARS. THE 
KENWOOD R-599 SOLID STATE RECEIVER AND T-599 HYBRID TRANSMITTER HAVE ESTABLISHED NEW STAN- 
DARDS OF PERFORMANCE, RELIABILITY, FLEXIBILITY, STYLING AND VALUE. 



THE R-599 RECEIVER: 3 microvolt sensitivity 
(amateur bands 1.8-21,0 MHz) • Dial readout 
to y 2 kilocycle • Special detectors for SSB, AM, 
and FM • Transceive operation with T-599 • 
Built-in 100 kc and 25 kc crystal calibrator * 
Built-in 500 cycle CW filter • Provision for two 
meter and six meter coverage with optional ac- 
cessory self-contained converters • Advanced 
"Space-Age" styling • Adjustable threshold 
squelch •Only $349.00 • S599 Speaker $16.00 



THE T-599 TRANSMITTER: Clear, stable, select- 
able side-band, AM and CW • 4-way VFO Flex- 
ibility plus Receiver Incremental Tuning (RIT) 
when used with the R-599 • Amplified ALC • 
Built-in VOX • Full metering, including cathode 
current, plate voltage, ALC and relative Power 
Output • Built-in CW Sidetone monitor and semi- 
automatic break-in CW • Built-in power supply • 
Maximum TVJ protection* Employs only 3 vac- 
uum tubes • Only $395.00 



THE KENWOOD 

TS-511S 

TRANSCEIVER 

The Kenwood TS-511S is a 
five band SSB and CW trans- 
ceiver packed with power 
and performance . . . offering 
features never before avail- 
able in its price range. For 
example: built-in VOX, crys- 
tal calibrator, noise blanker, 
receiver incremental tuning, 
1 kHz frequency readout, 8 
pole filter, stable FET VFO, 
dual conversion and acces- 
sory CW filter. 




FREQUENCY RANGE: 10, 15, 20, 
40 & 80 meters (Amateur Bands) 
D MODES: LSB, USB, CW D 
INPUT POWER: 500 watts PEP, 
300 watts CW nominal, D 
SENSITIVITY: 3.5-21,6 mHz band; 
0,5 uv S/N 10 db 28.0-29,7 mHz 
band; 1,5 uv S/N 10 db and less 
than 100 cps frequency drift per 
30 minutes after warm-up D 
SELECTIVITY: SSB more than 2,4 



KC {at 6 db} with 2 to 1 slope ratio 
CW more than 0,5 KC (at 6 db) a 
A.F. OUTPUT: more than 1 
watt (10% distortion) o TUBE& 

SOLID STATE COMPONENTS: 10 
Tubes, 1 1C, 37 Transistors, 4 FET, 
52 Diodes D PRICE: $415 .00 

PS 511S • Power Supply with built-in 
speaker $105.00 

CW 1 Filter $39.00 
VFO 5SS $105.00 



1 1240 W. Olympic Blvd., Los Angeles, Calif 90064 213/477-6701 
931 N. Euclid, Anaheim, Calif. 92801 714/772-9200 

Butler, Missouri 64730 816/679-3127 



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